Mitsubishi Eclipse Transmission Problem

This is a 1990 Mitsubishi Eclipse with a 1.8 m engine. It does have an overdrive and an economy option on the transmission. My husband rebuilt the motor on this car, and when it wouldn't start, he found out the computer was burned up. He had some fellas install a rebuilt computer for $200. The car started fine and still runs fine, but ever since the installation of this board, the transmission won't work. It won't go frontwards or backwards, either one, even though before rebuliding the motor, nothing was wrong with the transmission. Is it possible that something in the computer board messed up the transmission? If so, any suggestions? Thank you! Becky