To answer your question...yes , very likely other connectors that may have been near to failing have now done so by being disturbed.
There is a lot of help on here to point a home electrician in the right direction...if you feel up to it ..

If you can strip the fairing / tank off yourself , it takes no electrical skill to eyeball the connectors and the loom for obvious faults. Follow the new switch back and open any likely connectors one at a time as you go. Look for any burnt/ discoloured / loose or broken contacts . It may be obvious where the problem is. He may have also not reconnected the air box sensor or disturbed a fuel/ air line when removing the tank that is giving the fault.
Costs nothing but your time to have a look..

If not happy to do that , take it back to your mechanic , if you trust him ? , not sure I do, but I don't know him

. He did the swap but should really have investigated the resultant fault . Even if just to be able to give you a reason for it happening. Don,t expect any more time he spends on it to be free though , unless it turns out to be a problem directly with the new part or his mistake in not reconnecting something.
There is a relay kit available ( others will have to chime in as to where from , I have a gen 3 650 so not up on that ) to stop the kill switch/ headlight switch burning out again . But worry about that after sorting the present problem.
Sorry...All I have for the early model...