1996 Volkswagen Jetta Dancing Dash Gauges

This is a 1996 Jetta that we just put a 1995 transmission in. Prior to putting the 95 transmission in the car worked fine other than the transmission. I have been driving the car for about week now with just a few issues with the transmission that we are working on. But today I parked the car at the bus stop and when I went to start nothing happen other than lights came on clock reset to 12:00 and a no try to start, oh and the tac, odometer, fuel gauge and temputure were dancing I mean the arrow was going from one side to the other in an erratic manor. The dancing continue even after the keys were removed. We finally undid the battery and all stopped. We are stumped any body have some clues for us. HELP!