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Issue description

After having downgraded a phone from 8.9.3.x to a firmware version < the phone is not able to perform any upgrade / downgrade.

The phone just reboots, the normal update procedure doesn't start. At the end of the boot-up the phone shows a "Firmware update failed" error.


  • Any phone running an 8.9.3.x or higher firmware should not be downgraded to a version <
  • This may lead to a deadlock situation where the firmware works, but the phone cannot be updated anymore, except with a network recovery.
  • All versions < are affected by this update procedure issue.
  • If the downgrade is mandatory, use the as an intermediate firmware downgrade step, before you finally install the desired/known as affected version!
If you experience the deadlock situation do not open an RMA case, as this is not a hardware/flash issue. The phone can be recovered via a network recovery.