Radio issues , locking issues, and then not starting. Driving me mad

I had lots of problems like this. Had a mishap and let some of the smoke inside the ecu out once and some of the smoke inside the dash cluster too.
As we all know, when the smoke gets out fo the electronics, it stops working.

most likely missing some grounding in or around the ecu or the cluster so had to have something connected to the OBD port to make it run nice. after changing the cluster it all works fine.

When faulty I had to reprogram the key immo code from time to time and lots of other faults.

Could be that the stereo shorts something..
The original radio is pretty bad anyways so I would see it as a bonus that you will have to change it. I got a used head unit for cheaps, these audio car stereo fanatics swaps stuff all the time making good items for sale for me to buy,.

Either the radio is drawing a lot of current and dropping the voltage somewhere on that circuit or you have a bad connection and the normal current drawn by the radio causes the voltage to drop to the ECU or other devices.

The strange thing with the radio display suggested under-voltage, so perhaps it is a bad joint as normally something taking excessive current will blow the fuse.

Robin