[bmwcoder75]

I don't know how to calibrate it. I bought converter from customretrofit, I need to ask them whether it's possible to modify somehow.

All above codes are made and it still flickering. On original NBT EVO screen from F30 it works ok when coded to apix2.

They use a 0.5 euro voltage regulator from China.
Use a blade, remove the black tubing. Make sure you don't cut through the board or components.
You will see a small gold screw that might be glued. Remove the glue, then adjust the screw by turning it to the right (When the screw is on the top of the board).
Use your volt meter to make sure you are having 8.4v now. Might take a good few tries.
If the problem persists regulator might be faulty.