Why did you charge the battery externally for two days? Some of the things you say don't make much sense. When I charge a battery externally I know it is fully charged because the light on the charger turns from red to green. Doesn't that happen for you? Isn't that how all external chargers work? Mine cost me less than $10 US.

Shame the battery out trick didn't work. I know it worked for a couple of guys on here (can't remember what the threads were now).

I don't think it's a write-off by any means, not unless you've thrown it under the wheels of a truck. Just a case of waiting until/finding the right fix. But having said that, just hope the car charger hasn't banjo'd something.

I'm not a Maemo Wizard like most of the guys here, so all I can say is just try all the avenues.

never use a car charger to charge you phone (any phone you have)....
the best way it to buys extra battery or external charger....
once your battery is totally out then remove that battery & recharge it with an external battery while use your extra battery to turn your phone back to life....

to any member that always use car charger you will eventually realize that your battery life becoming shorter after a few time charging with it...this is cause by the car charger can drain the life power of your battery...although is charge you battery but car charger need more electric power to charge when a external/normal charger...the more electric it use the more your life battery will be drain...

try just flashing the kernel

Kernel was successfully flashed but ... same problem.
Damn, warranty is also out on this device ... stuck!

I had the same problem, my n900 went out of battery and then it keeps rebooting.
it only keeps on when i plugged it in usb mode, did u tryied that too?
just to know if we have the same problem and then try to find a solution for both of us.

You, sir, are full of ****.
I don't know where you got that idiot idea, but I can tell you that it's not true.
Remember: All charging in this phone is done by a TI bq24150 charging chip. It has three main modes: 100ma, 500ma, and 1.2A.
The 100ma mode will be used until the USB device connected to it allows it to use the full 500ma, or it's detected as a dumb charger(d- and d+ shorted) where it will draw up to 1.2A.

If your "car charger" isn't charging your N900, it means it's not going into 1.2A mode(n900 draws more than 100ma with screen on), because it's not designed to work with the n900. You need to either get one that /is/ designed to work with it, or short the D+,D- lines together in your USB cable or charger itself.

No charger can "drain" your n900, unless you happen to be using H-E-N and left the "boost" mode on. Which will drain it very quickly.