Regarding your point about not being able to charge your N900 (it gets stuck in the infinte loading-bar-loop):

This happened to my N900 when I had ran the battery down to nothing. It wouldn't charge, wouldn't boot past the dots. I tried to reflash a few times, but every time I tried, it just kept erroring out.

The only solution I found was to leave the device plugged into the wall charger for a few hours (overnight actually). Even though it wasn't loading the OS, the battery was still being charged slowly. Once I had enough battery, it allowed me to reflash both RootFS and EMMC.

Try leaving it plugged into a wall charger (the one that came with it) for a few hours. It'll continuously reboot for a few hours, but it should at least charge the battery enough to get you able to reflash.

Hope this helps!