DJM350 USB not reading (not the USB itself problem)

Hello! Ive searched far and wide for an answer but havent found anything so far. I have a DJM350 that works fine, except it won't read USBS, just doesn't recognize there's one in there it seems. Our normal repair guy said he thinks it's a software rather than hardware problem. It's definitely not the USB stick as it works on other players. Any ideas??? Is it possible to reset the 350 software somehow?