I bought 2 new, unused Nexus 5 as presents for my sisters for Christmas (not via playstore, but via a reseller. Still: new, sealed, unused.)
I unlocked, installed a custom recovery, rooted both devices without problems, then set up one in a smartphone-newbie-friendly way, which took quite some time. Then, to save me some time, I fear I made quite a big mistake: I made a nandroid-backup of the newly-setup device and restored/installed it on the second nexus (so I wouldn't have to change all the settings again, install apps, etc).
Unfortunately, this seems to have erased the IMEI on the second device (it shows as IMEI=0), so I can't connect to any cell service. Some googling leads me to believe that this might be due to a corrupt/missing EFS-folder, which, second mistake, I did NOT make a backup of beforehand. I know, it's my own fault - my thinking was: why backup, there's nothing backupworthy on the device *yet*.
I am not sure if the phone is still in warranty (and even if it was - I guess I voided that by unlocking/rooting?!). I want to re-iterate that I own both devices LEGALLY, I have the bill, I have the original sticker with the original IMEI - I just need a way to re-enter it. Any dialer-code for that? Any modify-able EFS-backups? Any other way?
Thanks in advance!
PS: tried so far & found useless: other simcard (not working) & simcard in other phone (working), so it's a device-issue; factory-reset;