Hello, I have a similar problem, I had installed the latest beta version of android N, and I had the problem that I do not recognize the imeis nor the sim card.
Reinstall the stable flyme 6 global.is  reinstalled and when it enters the recovery to do a hard reset, do not let me put my code or my fingerprint and nothing  say they are incorrect.
I have a flyme account but I do not have internet in my divice. I  since I can not access the device menu.
There is no way to enter another type of hidden recovery to delete all the device?
I need help, urgently
Thank you