I don't have the expertise to do any thing with the files. But I have experienced the frozen screen a few times. I tried a different cable and that seemed to solve the problem for a while.
One time I bypassed a Go4 app update and it did it to me. After I landed I tried to reconnect the tablet with the controller and I got a software mismatch notification so I never bypass an update anymore. The Go4 app has not been updated for the MP/MPP in well over a year and I don't expect it ever will be.
However I have always been able to fly the drone back VLOS with the controller or do a RTH. After landing and shutting down the Go4 app, the controller and the drone and restarting everything in sequence the controller and Go4 app linked OK as did the controller with the drone.
But as I understand it Your Drone and the controller don't link. Have you tried to go through the initial linking process as you would if you had a new controller? If you have and it didn't solve the problem I think you should definitely get in touch with DJI to get the ball rolling.
I bought a MPP in August this year and it turned out to be a lemon. I didn't want to go through the possibly lengthy wait while my drone was in shipping being fixed and sent back. So I sent it back to the merchant and purchased another MPP.
If I had the Patience to send it to DJI it would have cost me less. The main issue was with the video but it had other issues. It came with both batteries, AC and Controller, so low on charge they would not even register on the charger. Nothing was calibrated. I even had to calibrate the sticks, a hassle because the right stick would not go to 100% in one corner. But the video was the last straw.
It's replacement works great no problems at all.