did the repair shop fry my hu?

i have a JVC KW-AVX810 head unit (double din 7" touch screen), installed in a 1998 Lexus ES300. Iv had this unit a few years now and installed it myself. The unit has always worked without any issues. I put the car in a local repair shop to get the valve cover gasket, timing belt, etc. changed. When i picked it up the HU screen wouldn't turn on. The power button lights up(as it would when the HU is powered off) so i pushed the reset button and i can hear the head unit make noise. but the LCD screen doesn't turn on nor does the usb stick light up(that plugs in through a cable from rear of the HU).. The unit still turns on my amp's(via remote wire) Do y'all think the screen/HU is fried? i checked all power connections and they seem fine.. is there a fuse inside the HU that controls the lcd screen?? i contacted the repair shop and he said only thing he did was power off the unit by holding down the Power/ATT button. after trying everything i could think off i pulled the unit out and wired it directly to a battery. Same result, the small power button lights up but im unable to turn the HU on. Any advise what to troubleshoot next would be greatly Appreciated!! Also any info on what could have caused this to happen would be helpful. THANKS, hazed

You should have a fuse either in line or on the rear of the radio. Also it is possible that the radio is only receiving power and ground but NOT accessory.Gary Sather

yes: the only fuse is in the rear of the radio were the harness plugs into the head unit(10amp).. And that fuse is fine! (been replaced) As far as the car fuses goes: I eliminated them by taking out the whole head unit: running the accessory wire(red) and the constant power wire(yellow) to the positive(+) terminal on my battery and then running the ground wire(black) to the negative(-) terminal on the battery. i get the same result!    the only button on the unit that lights up is the (power/att) button on the faceplate of the unit. I push the rest button on the faceplate and hear the unit reset but the display nor any other button lights up.. iv tried everything i could think of but cant figure it out.. Looking back only thing i can think if was not having an inline fuse on the accessory wire.. but figured wireing that into the car radio fuse would be on.. idk i think its busted