2000 Audi TT Question: Starting/Electrical problem after rainstorm

My TT developed a strange problem after a pretty heavy rainstorm. The car is completely dead - no lights, no dash, no starter turnover-not even a click. After a half dozen attempts the lights came on when the key was inserted and the car started normally. It idled normally... I turned it off and immediately tried to restart - dead. I let it sit in the sun for a second day to "dry out" but had the same problem starting. Once it started I drove around for about 20 minutes, pulled in the driveway shut it off and had the same start problem. Any ideas?