The battery settings trick doesn't work on all players.
I have tried alot of them (while I was repairing them) and only a few of them would actually work.The reason why it's usually a combination of things.
1. Firmware settings
2. The board layout. Meaning.. The actual layout of the PCB has to contain a few extra parts what works in conjuction with the ATJ or AKA chip.
These chips has extra pins connected on the board to determine if the given unit is actually using the type of battery.
Some of the boards are having these parts, some aren't.
For example the ATJ2085 has 2 pins the BATSEL and the DCDIS pins which are determining the actual types of batteries being used in conjuction with the USB.
Sorry for the improper english description here but I'm trying to keep it as layman as I can.
For proper technical details, pls refer to the ATJ2085 pdf file I have uploaded to this site in the Downloads section.
cheers
p.s. If you want more play time just set the player to turn off the EL backlight in the Sys Setup/LCD Set/Blck, Set it to 5 and it will shut of the backlight in 5sec. If you leave it on 0 (default) it will not turn off yer backlight. Darkle is to set it to halfbright.It actually don't work on the lot of players.To conserve battery or like Tadad sez just stick in a bigger Lithium as big as you can fit or stick a really big, flat Lithium on the back of the player. lol :P
Anyways, good luck hehehe.