Hi everyone,
I’m having an issue with the left joycon on a switch I had to do multiple repairs. I replace the usb port and the fuel gauge IC. The joycon was working before the repairs and I tested the rail in another switch and is working. I can measure 5v and 1.8v on the ribbon but don’t know which chip around the battery connector and ribbon connector might be damage. I measure around and I can’t find any short. Appreciate any help.
For some reason I went around checking traces after a few hours connected the battery turn it on and the joycon is been recognized again 
… If somebody had this issue happen you can elaborate here but for now my issue is resolved on its own 
Left joycons have been linked to fan issues, they’re on the same circuit. Not sure of all the details. I remember reading some people “jumping” the fan with a short burst of voltage to reset it or something.
Thanks for the info. For now is working but I haven’t notice the fan turn on, so probably that’s why and it totally make sense.
there is no such thing as “jumping” a fan, all he’s describing is some burning out a dead diode that exists on some V1 boards directly behind the fan connector. If you don’t have charging on the right side joy con and the fan is not working, check for the diode and just remove it. Do yourself a favor and don’t randomly go injecting voltage into things without knowing exactly why and how to do it.
if you want to test your fan, just remove the heat pipe, turn the console on, and blow some warm air on the CPU die until you see the fan start spinning. You don’t need much heat or time to do this, if the fan kicks on circuit is fine. If the fan doesnt kick on you either have a dead fan or a problem on the circuit.