Thank you for that detailed reply.
So I think it is the electronic controller as well that is the problem since it would not turn on the compressor even if the unit has been turned off for a long time.
Usually, the temp sensor is the culprit plus the fact that it is cheaper to replace rather than the whole board.
I would assume you would have two of them.
One located in front of the evaporator
coil, ( the one that cools down) and one could be inside a soldered copper pipe on the upper portion of the evaporator coil. This is what we call the anti-freeze sensor. it senses that copper pipe and if it would freeze, it would turn off the unit.
Usually, we bypass these temp sensor by replacing them with rheostats.
Rheostats can be bought from local electronics supply. They have variable resistance and to simulate the resistance of a temp sensor, we buy 0 to 20 kilohms.
Normal resistance of temp sensor is about 12k-8kohms.
That is how you can bypass the temp sensor. But if still it would not work and the problem could be the board itself, then it is time to bypass the board.
I would suggest you get the help of your electrician friend, I would be mentioning some electrical terminologies of which they could be more familiar than you.
You would need to buy a rotary switch and a mechanical thermostat
for window AC from your local HVAC supplier.
You will replace the electronic controller with a mechanical one.
If you think you can do this, let me know and I will send you diagram which you can follow and could solve your issue here.
It would help me a lot if you can send pictures of the board showing the wires connected to it.
a picture of the terminals of the compressor and the wires connected to it.
a picture of the capacitors with wires connected to it,
a picture of the wires of the fan motor with the wires,
then we can one by one connect each wire to its proper places.
This would take time but I am sure, it would work.