This is known to all that PCR2.1 ECU must be unlocked first on BSL mode to use OBD.
If it’s locked then it still needs to be unlocked in bsl. It still won’t work writing the original file back via obd the car still won’t start the only hope and chance you have now is to get that ecu off get it connected up on the bench in boot mode and hope that it will still allow you to do a BSL unlock on the bench and then if it successfully allows you to unlock it on the bench. Also try and reflash it and read write it whilst it’s still connected up on the bench in boot mode that’s your only hope of recovering this ecu now and getting the car started again.
First you have unlock in bdm soldering resistor. Resistor 470ohm, resistor 1Kohm, cfg, boot, supply then unlock
If ECU was already unlocked or you did unlock in BSL, it must be a file issue. Contact your file provider. Check for DTC codes to help diagnose your problem.
In this case, you can simply rewrite the original file with mpps 18 or ODIS. The car works again. If you don’t have the original file, the quickest fix is to go with ODIS.
FYI: you can also write pcr2.1 by obd on bench with godiag tricore adapter