Hello,
I'm sorry to hear that you are experiencing issues!
The first thing I would recommend is updating the device to the latest firmware without the option to keep settings enabled. This will update the device and restore it to its factory settings.
If that does not help, I would recommend trying the factory reset procedure using the bootloader method described here.
If the device still does not boot after these procedures, please check if the device shows the same behavior without uploading your backup file. If that does not help, the device should most likely be sent for RMA.
Best regards,
DaumantasG