you can't say at what point the fuse blew. maybe it was after the tech finished the job. maybe it popped when you started the car. it's not like you can spot a failing fuse, you know. they just go. if they noticed it, they would have tried to sell you something. you've got this huge mistrust of dealers thing going on, and yet you think they'd pass up an opportunity to charge you for something? HA!
at any rate, i can tell you many stories of people who have tried to pin their car breaking on US because we fixed something completely irrelevant. the best one was the a/c compressor story... late spring we put a set of vcg's on someone's car and a week later it got hot out. they turned on the a/c. compressor made horrible noise. gee, that must be powerwave's fault, yeah, they were under the hood last week.
i've got more.