I had the same problem, i went to the dealer and i was out of warnenty by a few months, so they refered me to a 3rd party auido place. they wanted to rip me off on a repair, so i just pulled an sony X plode head unit from one of my dads old cars and installed it in the celica, i was able to yank out the 10 changer also, and all the wiring... Cheapest stero mod out of pocket yet!, plus its 10 times better then stock!!!!
If the 3rd party dealer wants anymore more than 50, to just look at the stero, your going to be out of atleast 100 to get it fixed, so just see what he/she is charging, Then look into an upgraded head unit (happy holidays, there gonna be cheap tomarrow)