I just went thru this tonight. I can't remember the exact things I did to fix it but this should get you there.
Download the firmware update from Pioneer unzip it and place the unzipped files on a basic thumbdrive then place the unzipped file on the drive. Unplug the unit for 10 seconds while unplugged then with two hands press the AUTO/DIRECT and power button then plug the unit it with the other hand you should see Recovery USB then slide the thumb drive in the front USB socket. It should soon start updating then when it says Success!! pull the thumb drive out and press power on the unit and off you go..