you will need to ground the tristate by soldering a cable onto the motherboard. don't worry, it is not very hard. look at this image:
You must login or register to view this content. and solder the 'GP2 (NOR_TRISTATE) to any GND point, hopefully this makes it stay on. i think it is also possible to just hold a cable to connect the two points, but soldering is definitely the better option