according to the service manual ------------------- U99 Hang-up Displayed when communication error has occurred between Main microprocessor and Timer microprocessor. Displayed is left until the [POWER] key is pressed. ------------------ WARNING*** do at your own risk!! To get into the service mode While the power is off, press TIME SLIP, STOP and OPEN / CLOSE simultaneously for five seconds. On the remote, press 0-2 and it will show the ROM version, region code, hard drive? This one is pretty interesting, 1-4: Encode and decode L1 signal w/o writing to HD or DVD This one is also interesting, 4-1: Shows the laser age in hours for both play/rec - if you get an ebay version, you can really check if new. 6-4: display working unit in hours - if you get an ebay version, you can really check if new. to get out of service mode, press power.