Same manual-timer and TVGOS-disabling advice applies to all three 2005 North American Pioneer models- the 531, 533 and 633 all use the same operating system and TVGOS. The 531 is simply a 533 without the front panel DV camera input, and the 633 is just a 533 with a larger hard drive. From a visual and user standpoint there are no differences between them whatsoever (repairing them when they break down is another story- the 531 can sometimes be fixed, the 533/633 are disposable deadweight.)
Try the above instructions, Nightingale, Pioneer owners have been passing them around this forum since the troublesome 531-533-633 were first sold five years ago. The manual-override procedure works on any of these models unless the machine has a corrupted/damaged hard drive.