I did something very stupid today. I helped a friend of mine to jump start his car. We somehow got the cables crossed, which resulted in a spark at my battery. His car was fine afterwards but mine has now multiple problems. It is very hard to start, has very low idle speed and the ABS light stays on. The car is a 1992 300 TE 4-matic, it started and ran perfect previous to my not so smart jump start attempt.
I checked the fuses and wiring. Everything looks okay, but I am afraid I did some damage to the more delicate electronics.
Any and all input will be greatly appreciated. It will most likely have to go to a shop, but I would like to have an idea of what I am looking forward to.

Thanks for Your response !