I had recently the same error and no imei shows on device/ about Reflashed whit latest global fiasco,but the problem remain.Then i reflashed(like i alway did)whit latest UK fiasco,restarted and it works like a charm!Maybe i am lucky and i don't have the hardware problem (althought my phone is 4 years old) but all of those who didn't try to reflash whit Uk version it's worth trying!