Any ideas about the history of the device?
K3 updates were differential (and atomic), meaning anything not matching the exact state it ought to be in for the expected FW version would make it fail without any effective changes.
Usually, that meant a custom invasive hack not designed to allow updates, but on stock devices, it's potentially a sign of hardware failure.
The system logs (;dm) will have details about the exact failure, which won't really help you if you don't have a backup.
That leaves
Kubrick, with the caveat that I seem to recall K3 recoveries being a bit more hit and miss than K5 ones.