iPaq won't neither boot nor load

Hey everybody!

My iPaq h6340 is behaving strangely. When connected to the wall plug, it boots for until about 30 % and then continues charging for about 1 minute (power button blinks orange). After that it just stops.

After reading through other iPaq related posts, I figured the cause was the internal battery, so just for the sake of trying, I removed the internal battery, attached to wires and connected a stronger battery (same voltage but higher mAh).

Strangely, there was no change in the iPaq's behaviour. It still will only boot to about 30% and then stop booting and stop charging after a minute (regardless of internal battery attached or not).

Anything I can do about that?

Thanks!