sunnys91 sorry to read that. For me multiple reboots after full powerdown somehow worked eventually. last time I had to reboot like 5 times and wait for LTE to connect and leaving it like that for a while locked, before attempting to unlock it, otherwise it resorted to a graphene logo loop. But it all sounds like woodoo magic.
and what's worse, once the device is in this state, it is impossible to re-flash it with a fresh firmware, as the bootloader is locked.
perhaps there should be some fallback solution to such situations (like a "safe mode"?), as they seem to be quite common?