Related, but no solution: How to restore my IMEI on Galaxy S if I don't have a backup of /efs?
My IMEI has turned blank after a nightly update, I can see it is blank when typing *#06# and I have no GSM functionality. Also baseband version is unknown.
I do have a backup of the /efs directory. I have restored the contents. But even before restoring, I checked the md5sum of the mps_code.dat file, and it was the same as the backup, so I didn't have my hopes up.
Nevertheless, I did a full overwrite of the contents with my backup. Rebooted, no change.
I have also tried to do a factory reset, reinstall Cyanogenmod, two different versions, wiped cache, Dalvik. Remove the battery, SIM card, USB cable.
I am willing to install the stock firmware, if I could find it, or patch the modem firmware somehow. Where should I go from here in a situation such as this one?