Jetson Orin NX Black-Screen Rescue — Postmortem & Reference Guide

Device: NVIDIA Jetson Orin NX on a Yahboom carrier board (clone of the official P3768 devkit; unfused board) OS: L4T / JetPack, kernel 5.15.148-tegra, upgraded 36.4.3 → 36.4.7 mid-incident Date of incident & rescue: 2026-07-05 Outcome: ✅ Fully recovered, no data loss, no reflash of the SSD

This document is the distilled reference for the whole rescue. The blow-by-blow working log is in RESCUE_NOTES.md; diagnostic evidence is in bootdiag*.log, repair_run*.log, and openclaw_audit.log in this directory.

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TL;DR

An unattended PackageKit upgrade of ~190 packages (including the entire L4T stack) was interrupted by a power-off mid-transaction, leaving the Jetson's userspace half-configured and the machine apparently dead (black screen). The rescue never reflashed the SSD. Instead, the SSD was attached to an x86 Ubuntu host PC and repaired file-level with three fixes:

1. Finish the interrupted dpkg transaction inside a qemu-user-static aarch64 chroot.
2. Point extlinux.conf at an initrd that actually contains NVMe drivers (the upgrade had clobbered /boot/initrd with a minimal one that couldn't mount the root disk).
3. Keep GPU/display modules out of the initrd (an initramfs hook), because loading the Tegra DRM stack at ~2 s inside the initrd probe-fails permanently and results in a black screen with a fully booted system behind it.

Bonus finding: an OpenClaw AI gateway running on the device was a vendor leftover from Yahboom's pre-sale demo (not an intrusion) and was removed; the account password was changed since the vendor knew it.

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Symptoms (what the user saw)

• Power on → NVIDIA logo → black screen. No desktop, no text consoles (Ctrl+Alt+F1–F6 dead), at various stages no LAN presence either.
• The UEFI bootloader could see the SSD and listed it as a boot option.
• Depending on the phase of the rescue the failure looked different — this was actually four distinct problems stacked on top of each other (see below).

The four stacked root causes

1. Interrupted unattended upgrade (the original sin)

At 10:04, PackageKit auto-started an upgrade of L4T 36.4.3 → 36.4.7 plus ~190 other packages. The machine went down at ~10:11 mid-transaction (the apt history.log entry has no End-Date). Result: systemd, udev, kmod, openssl, all 44 nvidia-l4t-* packages and more left unpacked/unconfigured, plus pending ldconfig/initramfs triggers.

Key insight: the boot files were never corrupt. /boot/Image was a valid kernel, the PARTUUID in extlinux.conf was correct, and /var/log proved the machine had booted fine for days before. "Black screen" was broken userspace, not a broken bootloader. Diagnose before reflashing — this saved all the data on the SSD.

Fix: attach the SSD to the x86 host PC and finish the transaction in an aarch64 chroot (qemu-user-static + binfmt). All 1120 .debs were still in the SSD's /var/cache/apt/archives. Scripts: repair_ssd_dpkg.sh and repair_ssd_dpkg2.sh. Essentials for chrooting into an L4T rootfs from a foreign host:

• Bind-mount /proc, /sys, /dev.
• Add a policy-rc.d guard so postinst scripts can't start services.
• Create NVIDIA's .nv-l4t-disable-boot-fw-update-in-preinstall marker so the l4t debs don't try to touch boot firmware from the host.
• Then dpkg --configure -a --force-confdef --force-confold, and verify with dpkg --audit (must come back empty).

2. UEFI had marked the boot chain bad

After the crash and a few failed boots, UEFI set "OS chain A status" to bad, which produced a totally silent boot (blinking cursor, zero kernel text) — easy to misread as a deeper failure.

Fix: in the UEFI menu, set "OS chain A status" back to NORMAL. Boot messages reappeared immediately. Check this first whenever a Jetson boots to a blinking cursor with no text at all.

3. /boot/initrd had no NVMe drivers → can't find PARTUUID=…

The interrupted upgrade's nvidia-l4t-initrd package unpack overwrote /boot/initrd at 10:10:54 with the minimal devkit initrd, which contains exactly two kernel modules (Realtek NIC drivers) — no nvme.ko, nvme-core.ko, pcie-tegra194.ko, or phy-tegra194-p2u.ko. On this kernel those are all modules, not built-ins, so the initrd literally could not see the NVMe disk. The pre-crash initrd that used to boot the system was gone.

Fix: no rebuild needed — the dpkg repair had already generated a proper initramfs-tools initrd (/boot/initrd.img-5.15.148-tegra, verified via lsinitramfs to contain all four modules). Both INITRD lines in /boot/extlinux/extlinux.conf were pointed at it (backup: extlinux.conf.pre-initrd-fix).

4. The new initrd loaded the display stack too early → black screen #2

With NVMe fixed, the system booted fully — GNOME session, DHCP, sshd all running — but the screen stayed black and VTs were dead. Comparing the failing boot against pre-crash working boots in kern.log.1:

• Working boots: host1x/tegra-drm load ~6–8 s from the rootfs via udev → /dev/dri/card0 appears → X's nvidia driver initializes and pulls in nvidia-modeset/nvidia-drm at ~13 s → display works.
• Failing boot: the initramfs-tools initrd (MODULES=most) had bundled the whole DRM/GPU stack. udev inside the initrd loaded it at ~2.1 s; VIC/NVDEC/NVENC/NVJPG/OFA probe-failed (failed to init devfreq: -22) in the barren initrd environment — a hard error with no retry after pivot-root → no /dev/dri/card0 → Xorg (EE) No devices detected → black screen. The same missing devfreq/actmon sysfs also explained the nvpower.service / nvpmodel failures seen scrolling by.

Fix: initramfs hook /etc/initramfs-tools/hooks/exclude-display-modules that prunes kernel/drivers/gpu, updates/drivers/gpu, updates/drivers/devfreq, and updates/nvhwpm.ko from every initrd build, then a rebuild via the qemu chroot (script: repair_initrd_drm.sh; backup: initrd.img-5.15.148-tegra.pre-drm-fix). Because it's a hook, it survives future kernel updates.

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Side quest: the OpenClaw vendor leftover

An OpenClaw AI gateway was found running (and crash-looping with WhatsApp 401 errors) on the Jetson. Audit (openclaw_audit.log) showed it was installed 2026-03-18 by the vendor (hostname still yahboom at the time) as a Chinese-ecosystem bot demo (Bailian/Qwen, QQ, Feishu, WhatsApp). They sanitized it on Mar 26 before handover but forgot to disable the service. No intrusion indicators — no foreign SSH keys, empty crontabs, no logins after March.

Cleanup performed: systemctl --user disable --now openclaw-gateway, npm -g uninstall openclaw, rm -rf ~/.openclaw, and passwd (the vendor knew the shipped password — always change it on any pre-imaged device). Vendor Wi-Fi profiles optionally removed.

Lesson: treat any vendor-imaged device as untrusted until audited — check enabled services (system and systemctl --user), authorized_keys, crontabs, and change all passwords.

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Diagnostic techniques that paid off

Technique	What it proved
Read apt history.log / term.log on the mounted SSD	Found the interrupted transaction (missing End-Date) — the true root cause
dpkg --audit in chroot	Enumerated exactly what was half-installed
Unpack the initrd (lsinitramfs, cpio) and check modules.builtin	Proved the "can't find PARTUUID" error was missing NVMe modules, not a GPT/UUID problem
Diff failing boot vs. pre-crash boots in kern.log.1/syslog.1	Pinpointed the too-early DRM module load (2.1 s vs 6–13 s)
Read the journal/syslog from the SSD on the host PC	Showed the "dead" machine actually had a full GNOME session, DHCP lease, and sshd running
CapsLock LED toggle test	Cheap "is the kernel alive?" check on a black screen
File timestamps (/boot/initrd mtime 10:10:54)	Tied the clobbered initrd precisely to the crashed upgrade

Also useful: the Jetson gets DHCP on eno1 even with a black screen — ssh jetson@192.168.0.39 / nknu.local. Note the Yahboom carrier uses a Realtek NIC, so don't filter LAN scans by NVIDIA MAC OUIs.

Rescue infrastructure built along the way

• Bootable USB rescue stick (58 GB drive, L4T R36.5.0) flashed with l4t_initrd_flash.sh -c tools/kernel_flash/flash_l4t_external.xml --external-device sdd1 --direct sdd jetson-orin-nano-devkit external with the board in Force Recovery Mode. Kept as a permanent rescue tool.
  • Gotcha: the flash target for this board on R36.5.0 is jetson-orin-nano-devkit (covers Orin NX too); jetson-orin-nx-devkit does not exist.
  • Gotcha: disable GNOME automount on the host first (gsettings set org.gnome.desktop.media-handling automount false, same for automount-open) or it races the flash tool and fails with "partition in use". Re-enable when done.
  • The "Please install the Secureboot package" warning is harmless on unfused boards.
• qemu-user-static aarch64 chroot on the x86 host — lets you run dpkg, update-initramfs, etc. directly on the ARM64 rootfs. Slow but reliable.
• All diagnostic/repair scripts in this directory are re-runnable references: bootdiag*.sh, repair_ssd_dpkg*.sh, repair_initrd_drm.sh, openclaw_audit.sh.

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Standing maintenance rules (post-rescue)

1. Unattended upgrades are disabled on the Jetson — the entire incident started with PackageKit auto-upgrading L4T. Apply JetPack/L4T updates manually, at a time when a power loss won't hurt, and let them finish.
2. After any future L4T/JetPack upgrade, re-check /boot/extlinux/extlinux.conf: the nvidia-l4t-kernel postinst rewrites it. Verify DEFAULT is still JetsonIO (carries the dual-IMX219 camera FDT/overlay) and INITRD still points at /boot/initrd.img-5.15.148-tegra (or that /boot/initrd finally has NVMe modules). The exclude-display-modules hook itself survives updates.
3. Keep the backups on the SSD: extlinux.conf.pre-initrd-fix, initrd.img-5.15.148-tegra.pre-drm-fix, initrd.img-*.pre-drm-fix.
4. Keep the USB rescue stick. It boots the Jetson independently of the SSD and doubles as a known-good file reference (same BSP).
5. If a future boot dies inside the initrd, the initramfs-tools initrd drops to a busybox (initramfs) shell — cat /proc/modules, ls /dev/nvme*, dmesg | grep -iE 'pcie|nvme' will show what's missing. (The stock L4T initrd does not offer a shell.)
6. Fallback of last resort: the original Yahboom Orin NX image (Frank has the ISO) — contains the factory initrd and full carrier-board setup. Never needed during this rescue.

Timeline (2026-07-05)

Time	Event
10:04	PackageKit auto-starts L4T 36.4.3→36.4.7 upgrade (~190 pkgs)
~10:11	Machine goes down mid-transaction; /boot/initrd already clobbered (10:10:54)
afternoon	USB rescue stick flashed; SSD attached to host PC; root cause found in apt logs
~17:34	dpkg repair runs 1 & 2 complete in qemu chroot; dpkg --audit clean
evening	Boot test #1 fails: can't find PARTUUID → initrd diagnosis → extlinux.conf INITRD fix
night	Boot test #2: system boots but black screen → journal analysis from SSD
~20:00	Early-DRM-load root cause confirmed; repair_initrd_drm.sh applied & verified
20:16	OpenClaw audited: vendor leftover, cleanup plan prepared
after	Final boot: display works, system fully recovered; OpenClaw removed, password changed