deeryders

A tech at my shop was putting in a remote starter in a 2002 Lexus ES300. He started off with the heavy gauge wires. Before he was on his last wire the car would not start. We triple checked all the fuses and double checked the wiring. As he was starting it, I lightly tapped the alternator and the car started. He turned the car off and yet again I had to tap the alternator for it to start. This went on 2 more times (it was cold out and we did not want to keep the car running in a closed garage). The last time we tried this it did not work. At this point the car was towed to Lexus and the mechanic there said it was a surge in the car which blew a 15amp fuse which killed a cell in the battery which killed the starter. Now they are trying to bill us 700$. The car has over 120,000 miles on stock starter. Perhaps it was ****ty timing. However, I want to know from you guys is that - from what the mechanic said, is that even possible? Isn't the fuse supposed to protect from the surge? How does this all link back to the starter?
Thank You.