I think it would be nearly impossible to remove the dash with the steering wheel installed. Even when following factory work instructions it's a bit of a juggling act. I know this because I've done it many times. If the wires to the combi-switch were routed incorrectly during re-assembly, they could easily be pinched or crushed, causing the short circuit you experienced. I think your guy made a mistake. Have someone remove the under-dash panel on the drivers' side and you'll be able to see the wires exit the steering column. This is probably where you'll find the problem. Good luck and let me know how it goes.