2.5 years later I made another attempt at getting Auto Power on enabled on my 8" widescreen lilliput (model 889GL-80NP/C/T). I couldn't get into the factory menu at all until I removed the battery from remote control.
Step 1 - bootup carpc to provide VGA signal.
Step 2 - disconnect battery from remote control and plug back in.
Step 3 - disconnect power from back of monitor and plug back in.
Step 4 - power on monitor by pressing button on monitor (do not use power on button from remote).
Step 5 - wait 2 seconds and on remote press 588998 (approx 5 seconds to key those in)
Step 6 - wait for underscores and on remote press 1290210
Step 7 - on remote press 5 to exit
Step 8 - power off and you're all set
It took about 3 attempts before I got in.