Hi Ive had a similar thing recently, I washed the carpets in the car with a vax carpet cleaner, and shortly after started getting shocks plus lost the instruments, the cabin temp lights were dimming, this was with ignition on or engine running. Noticed a footwell light pulsing as per cabin heater display removed it and problem solved. I can only assume that with the damp carpets condensation formed in the fitting and caused the short. Is your car damp inside, and can you see any clues such as pulsing lights or gadgets not working?
Good luck