You must find a way to charge your battery because to finally realise what is wrong will need at the very least a charged battery, if you have a mobile shop near you then get them to charge battery at the very least, i know from my N900 you can plug the usb in and it can take a few minutes for the charge to start being recognised on a flat flat battery.
If your in doubt then take it to your nearest Nokia care centre because even if they dont have the N900's in aussie they will have an engineers flow chart to find out the problem. Sorry all i can suggest GOOD LUCK ok.