[BFW-8838] [BUG] Bootloader hangs on MK4S after upgrade to 6.5.6

[oxivanisher]

Printer model

Prusa MK4S

Firmware version

6.5.6

Upgrades and modifications

None

Printing from...

USB

Describe the bug

I sucessfully flashed the firmare on my MK3.5 and C1, but flashing the MK4S results in a bootscreen where the "loading bar" stays approx. in the middle. I redownloaded the file several times and tested multiple USB keys, but always the same result. I had to use the double-click method after the first flash, but the result is always the same.

How to reproduce

Download the 6.5.6 release to a USB stick and flash teh MK4S

Expected behavior

The printer boots up sucessfully :)

Files

No response

[H0Z0]

Confirmed. After updating FW, it won't restart. It gets stuck at the bootloader screen. Reloading the previous 6.5.3 FW makes the printer work again.

[Ro3Deee]

fw 6.5.6 seems retracted now...

[fhempy]

Same issue here. How did you reload 6.5.3?

Edit:
https://help.prusa3d.com/de/article/downgrade-der-firmware-core-one-mk4-s-mk3-9-s-mk3-5-s-xl_725930

[danopernis]

@oxivanisher @H0Z0 thanks for the swift report, I was able to replicate this on one of our machines too.
@fhempy thanks for the link to downgrade guide, here's the English version for anybody experiencing this issue.

I am investigating this right now. My current hypothesis is that this happens only on older xBuddy revisions. If true, this also possibly affects MK3.5, MK3.9 and upgraded CoreONE.

To confirm, can you share some debug information with me? Info -> Version Info -> Buddy Board and Info -> Version Info -> Serial Number (the part after / should be enough if you don't want to share entire serial number)

[H0Z0]

Yes, this is the older HW.
Buddy Board 27
Serial Number /14
Love Board /34
xLCD is also the older one, no serial number.

[oxivanisher]

Yes, I think also that I have an old version:
Buddy Board: 27
Serial Number: /14
Love Board: /36 (This is a replacement part if I remember correctly)

[Ro3Deee]

I am investigating this right now. My current hypothesis is that this happens only on older xBuddy revisions. If true, this also possibly affects MK3.5, MK3.9 and upgraded CoreONE.

This is why a Release Candidate should always precede, by a week, a stable release (except exceptional urgent ones). Some of us will try the RC...