1. Using root explorer locate the /efs/imei/ folder. In that folder there should be a file called keystr. In my case the file was missing which is why the lock screen was missing and was causing my problems.
2. using root explorer create a new file called keystr
3. also in root explorer open the file keystr in text editor and type ON
4. now go into hex editor and locate the /efs/imei/keystr file.
5. using hex editor the first two values in green should be 4f and 4e. all others should be 00.
6. make sure you save the file.
7. reboot.
Hatte Anfangs das selbe Problem nach dieser Anleitung (die aus Sammobile) ging es wieder .