3s is very fixable. Had my scroll-wheel locking up, because of a fall. Turns out the inner workings of the scroll wheel were broken, jamming it. Removed the broken pieces, glued it, working fine again..

I believe it. It looks more than doable from that ifixit.

I've replaced the switches in a Logitech G305, and it wasn't too bad.

The mouse itself was fairly straight forward to get into. Move the pads, undo the screws, a little time probing around with a spudger.

Borrowed the switches out of a Raspberry Pi mouse I had in a spare parts bin. Opted to replace the feet at the same time.

Some minutes soldering later and reassembly, worked as well as it always had.