Ever go buy fuses? That's likely the culprit. Heck.. I bring needle nose pliers to the JY if I'm low on fuses.

Ok.. so we doubt any wires were snipped/nothing malicious or cooked wires are likely a problem. Does that sound fair? If so.. I'd aim toward relay. Find the one for the defroster and check all inputs to it. The light issue has me thinking something in in a location where it doesn't belong.