Last update.

I just go my phone back from a licensed Nokia Service Center. They said that the only way to repair the phone is to completely replace the motherboard which is really expensive and i can buy a second hand N900 for less.

I am really skeptical about this since the phone works fine if i use a charged battery with the exception of the device heating up a bit and the battery getting drained faster then usual but there is nothing i can do about it.
Once again, thanks for the help guys