PROBLEM ON START WINDOW AC

A bad smell is a blown capacitor (most likely on the power broad)
Take the back off and look for bulged or leaky capacitor, and swap it out.

just about all on the market use start/run capacitors

I have the same model, I need to replace the capacitor but I can't find the valve of it

salaams ,
check the capacitors(running) and also fan capacitors. or in the last check the compressor may be overheated.

If you are able to unsolder the unit you can probably pick up a capacitor at Radio Shack or Electronic Shop. Just buy one that has the same capacity.

Compressor may be locking up. Run capacitor may be weak or loose wire. Sounds like major voltage drop off as unit head pressure increases.

Replace reset switch or bypass it to make sure it is the problem. Check for low voltage while the unit is on. Shoud stay above 105 vac

Does not sound right to me.My guess after doing what every he was doing he probably installed a start capacitor or repaired a burnt wrie, got the compressor running and charged for a lot of guess work. Just guessing.