Nintendo Switch Joycon Issues


 * If Joycons aren't charging, check if the fan works, if not this is an issue with fan circuit, see this guide.
 * Next check for junk/corrosion in the Joycon connectors on the Switch side, and the Joycon's side.
 * If the joycon only works when connected, sometimes the connection to the battery might have got loose, possibly if you've replaced the joystick to fix a drifting controller. Open, disconnect battery and reconnect.
 * Otherwise replacing the DC-DC component labelled "PU" on the flip-side of the board should work, each Joycon connector has its own corresponding component closest to it (see photos)