[cparke]

I was right that since the player's USB disk was still available, as well as the player would still play music even though the unit now had a constant white screen indicates that a firmware update is not what the player needs. In fact, this experience might help some others who have reflashed with the right firmware but now a white screen neverthless.

Turns out I was right about disconnecting the barttery to get a hard reset.

I seems the reset button on the unit doesn't cut the power but rather just signals the processor to reboot. Volatile memory is not cleared! Since the wires coming out of the battery on my unit are soldered into the board and I didn't want to cut and reconnect them, instead I used the small screwdriver to short the batteries +/- terminals to deprive the board of power for an instant, all that is needed to clear all volatile memory in the components. After I did that, the unit would not power up at all, like perhaps I had fried it. However, once connected to the PC via USB, the color display came online! Wow - unit is saved.

Regarding how I did this to myself, obviously I don't recommend overusing the reset button, holding it a very long time, or holding it in conjunction with other buttons, because I came very close to bricking the unit by doing that. The reset button is just a re-boot button really, not a power button (unit always has power). It seems that any minor file system inconsistency, or filename with control characters, or corrupt audio/video on the disk will cause these players to either keep rebooting or lock you out from accessing applets. The proper fix is do something to the disk USB to try to find the offending file. In the worst case, empty the disk and then try to start the apps to make sure you get "Empty Disk" and then start re-adding your files until you find the bad file that caused (or re-causes) the problem. The firmware is very finicky - on one of the replacement players I got, a format using Linux mkdosfs command would cause that player to continuousely re-boot, but doing the identical format using Windows itself restored the device (I'm not sure what the difference in the FAT32 could be!)

So, I'm back in business with my MP4 player now, and hopefully others will benefit from this knowledge.