Alright, so first of all, my Samsung Galaxy SIII got some damage, and then we brought it to a repair shop. They changed the motherboard, and then returned it to us and it was working fine. The only thing is, the Android version is still on 4.0.4, and whenever I boot the phone, a T-Mobile bootloading screen appears, and it annoys the hell out of me. So, I flashed Android 4.3 Jellybean using Odin. Yet, after the update finishes, the phone won't make a text or a call. It always says 'Not Registered On Network'. So here are some notes of the phone's status...
1. I tried to use Ariza Patch, yet it didn't work.
2. The IMEI's number is not changed to 0000 or anything, it's just a 15-digit number and has a '/01' at the end of it.
3. The signal is full.
How could this be fixed? Is there anyway to fix this? It would be very much appreciated. Thank you!