Toyota Repair: 02 Sienna Transmission, transmission repair shop, remanufactured units

Question
Sianna's transmission started slipping and progressively got worse to the point of not running at all. Took it to transmission repair shop. According to them they replace worn out parts, but they stated that it was an electrical problem (may be a fuse) that kept it from running properly. Do happen to know what could be the problem if it was a electrical component that could cause this malfunction.

Answer
I doubt that it's a fuse, did the transmission shop actually charge you for a repair then didn't fix the problem and told you it was a fuse?
The why did't they check the fuse first? Sounds very unprofessional and a little like theytook advantage of you.
These transmissions are electronically controlled and an electrical fault would turn the check engine light on, is this light on?
Toyota stopped a long time ago to repair these transmissions at the dealer level due to their complexity, they are usually replaced with remanufactured units, having one of these transmissions taken apart and replacing parts is in most cases a waste of money because most transmission shops are not familiar with these types of transmissions.