R170 2.3 - won’t start

[daithestag]

Right guys - need some serious help - after doing some very minor work on my SLK R170 2.3 - I have just recently changed my heater blower and now working great car started and I started and I took it in and out of the garage a few times and all ok - I had an MOT booked this week so I had to replace a side light and while I was at it I fitted 2 led lights using a piggy back off fuse 31which is labelled cigar illumination when ignition is switched on - I was struggling to find a earth so ignition was probably in the ON position far to long anyway went to start car and no ignition lights apart from handbrake dash light - no LED read out on the clocks on the dash - no hazards, no fan , and no central locking - when ignition is on I can hear a motor ( possibly abs ) under bonnet but roof works ? called recovery who wasn’t an electrician just a basic fitter who checked all fuses but found all to be ok and he was stumped so at the moment car still won’t start - I’m thinking I’ve burnt a module or something similar out while doing the lights maybe ? Any MB master fitters out there ????