Electrical Help Needed

[sptt]

I bummed out I was trying to install on of those cheap keyless entry systems to the pump underneath my seat in the back of my 300E and I must have shorted something out. Now there is no power going to the pump (I tested the + and - for 12 Volts...or less...it actually was working when I put it back together last night and then today...it stopped) and my rear seat light doesn't come on when I push the dash button for it. Actually, the front seat lights turn on??? I replaced the A fuse which controls all that stuff but still getting same result. Anyone have any ideas or where I can check next? Did I short out a relay switch or something? Please help!!! It was all perfect before this.

Update:

Thought I had checked all fuses but C3 had blown. Replaced that one and all is fine again.