Hi everybody! Just finish to fix an old logitech X-230 model.
Same issue as roberto8978 for me, it save me a lot of time actually, I was begin to test power component to find the failure.
The cable from the remote control was faulty --> 1 wire (green) with erratic behaviour, tricky to find it when doing a continuity test. Crappy cable (and design btw but don't ask to much for <30€ probably). I change it with a complete shielded cable (gnd braid), the original one is not just a wire acting as a gnd. I think it improve a little bit the gnd noise actually. I post some pictures too. Thx for sharing guys.
For information the whole fix took me still more than 2 hours! Anticpate thermal paste if you dissamble the heat sink.