Help troubleshooting a ST1 computer


After a charge I noticed the display did not seem right. Specifically, things were not charged up. I pushed some buttons and the display went kooky. I figured it needed a new battery, installed, and then recharged. Everything seemed fine. Then I went for a ride and the speedometer was acting crazy. Speeds read 80-120 MPH! I checked everything, tried to do a reset (9999) but that said error, checked the tire size (it was 26) and disconnected the 3 cables connections at the rear wheel and the the right brake to insure the connections were OK. Same problem. Any ideas?