Somewhat related to Mark's above post.
A few years back, my top stopped working also, just like your symptoms.
I finally got around to troubleshooting, and noticed that the trunk light was no longer working.
That was EASY, I thought. The bulb checked good, no 12v to the light. I found fuse 9 blown in the under hood fuse box. Replaced the fuse and the light and the TOP worked again!
Turns out fuse 9 also supplies 12v to the BCM.