I managed to open the SIM slot of the phone and inserted a working SIM from another phone. Since the SIM was not detected at all, I decided to give the nightly CynogenMod 12.1 on the phone. Again via SFTP to SSHDroid in the LAN.
The phone booted into CM 12.1, but the Google services (especially Play Store) were crashing, so I had to upgrade the GApps and after the ZIP from OpenGApps ran into an error in Recovery Mode (CWM), the arm binary from CGApps was ok:
- Download CM 12.1: Link out-of-date
- Download latest ZIP from GApps for arm architecture (View Raw): https://github.com/cgapps/vendor_google/tree/builds/arm
- Copy both ZIPs to /sdcard using SSHDroid.
- Uninstall Google Apps (GMail, YouTube, Play Store, Hangouts) for all users using Settings/Apps.
- Boot into Recovery (CWM) with Volume UP Button.
- Install both ZIP files from /sdcard/ location.
- Clear Cache using Recovery.
- At least the Play Store should no longer complain/crash and can be updated. But I needed to recreate the Account Information.
- Other Apps complaining/crashing should be uninstalled for all users in the Settings/Apps and reinstalled by using the Play Store (GMail, YouTube, Hangouts, …).
I hope, I did not forget a step in this CM 12.1 upgrade process. So far, I did not need to do a firmware reset flushing /data.
The bad news is, that my E975 is still not detecting the SIM card, but I can’t tell, if it’s a hardware related (slot defect) or a software issue, I will keep updating nightly CM 12.1.