Switch: the Joy-Con is no longer recognised when attached
The Joy-Con clicks in, the console doesn't see it, and it no longer charges. Before buying a new controller, look at the rail.
The rail on each side of the Switch holds ten spring contacts that power the Joy-Con and talk to it over a serial link. After thousands of slides, the contacts wear or bend; a sugary drink corrodes them too. The result: the controller is only recognised over Bluetooth, detached, and no longer charges on the console.
The simple test
Detach the Joy-Con and use it wirelessly. If it works perfectly that way, the console rail is at fault. If the Joy-Con doesn't work either way, it is the controller (its own rail, battery or board).
The repair
The rail is replaced by removing the back shell and shielding; no soldering, one ribbon cable and a few screws. The part is cheap and the job is done by appointment in under an hour. The “Joy-Con rail” price is on the prices page for the Switch V1/V2 and the OLED; the Lite has no rails.
Good to know
The Joy-Con's own rail can break too (the little latch that locks the controller). It is replaced the same way. And if the stick drifts, that is something else again: see our article on stick drift.
Also worth reading
Switch that won't charge: the cheap charger and the M92T36 chip
A Switch that stays black with a flat battery often has no battery problem but a charging-circuit problem. Where it comes from, and why it can be repaired at component level.
Nintendo Switch 2: what we already repair at the workshop
Screen, USB-C port, battery, fan, game-card reader: the first Switch 2 repairs, and what we are still waiting for on the parts side.
Switch OLED cracked screen: glass alone or full panel?
On the Switch OLED the touch glass and the display panel are two parts. Depending on what is broken, the repair doesn't cost the same. How we decide.