I was able to contact a tech at Genesys (now owns STEC).
He suggested isolating the pitch computer to see what happens.
I disconnected the Pitch computer and tried turning it on. Viola - functions OK with just the roll side connected.
I opened up the pitch computer to check the internal fuse - it was bad. Replaced the fuse - checked the wiring for shorts, all OK and functioning properly again.
Thanks to all for their suggestions!