Go 7 bootloop

[gleboss]

Hi!

Yesterday I picked up my Onyx Boox Go 7 and noticed that the battery was completely drained. After charging it, the device no longer boots properly.

Current behavior:

• It shows the BOOX logo
• Then the loading animation with dots
• After a short time the animation freezes and the device reboots
• This repeats indefinitely (boot loop)

What I already tried:

• Entered recovery mode
• Wipe data / factory reset
• Tried reinstalling the latest firmware using
  

  adb sideload update.upx

• The update fails with "signature verification failed"

Could you please suggest possible ways to recover the device?
I saw that you sometimes use custom recovery or EDL tools for BOOX devices and wondered if something similar could help here.

Any advice would be greatly appreciated.

Thank you!