Please Help, Fixing broken IMEI on Samsung Galaxy S6 G920T

Hello, I have a Samsung Galaxy S6 SM-G920T which has some strange problem with the IMEI. It comes up as 350000000000006 as the IMEI And it says "Not Registerd on Network" I tried writing a new cert to the phone but it fails every time, I also tried repairing the security and any other thing I could try but I can’t seem to fix the issue. The phone is actually SM-G920T1 (Metro PCS) but I flashed the Tmobile software on it thinking it might fix the issue.

How can I use Octoplus box to fix this issue?

Thank you