1. Check your fuses on the rectifier board under the playfield.
2. Check the small fuse on the solenoid driver board.
You should get some of your displays going.
4. You'll probably have to rebuild the high voltage section of the solenoid driver board. (or you can buy a rebuilt board from me)
http://www.bigdaddy-enterprises.com/ (Bally High voltage regulator kit)
3. Use this source for trouble shooting the individual displays.
http://stevekulpa.net/pinball/bally_disp6r.htm (Bid Daddy also sells display repair kits)