I will relay this to my mechanics, it‘s tough to be at their mercy
Electrical problems like this are very difficult to troubleshoot but if a little educated guesswork fails to find the fix then it’s time for a return to the very basics and a step by step illiminaton to things that are right with the system until you find what is wrong.
It’s slow boring and expensive but it’s the only way to get to the bottom of the problem.