If the Flipper's firmware is corrupted, the device can be restored using the built-in DFU boot loader. This bootloader can't be changed when updating the firmware, so the recovery method is suitable for such cases:
The device may not work if the battery is low. Connect the device to the USB and try to charge the battery before attempting to restore the firmware.
To activate the built-in bootloader:
When connected to a computer in recovery mode, there will be no indication on the Flipper screen. If the device successfully enters recovery mode, it will appear in the Device Manager as DFU in FS Mode.
Check the connection in Windows:
By default there is no driver for the Flipper DFU device in Windows, it is installed automatically when you install the qFlipper.
The qFlipper utility automatically performs firmware recovery if it detects a Flipper connected in DFU mode.
To restore the firmware: