The damned thing doesn't even get into Update Mode. As for another battery, can I order and use this? http://tinyurl.com/n900bl5j The model's the same, but the phone model is something else.
PS: What's an offline charger? The one you plug into the wall outlet? Didn't try that yet. *facepalm*

EDIT: With the wall charger, it turns on for a few seconds! I get a super-dim Nokia screen, like the one on the Update Mode.
EDIT 2: The exact thing that happens is like this:
Connect charger >few seconds> Dim Nokia Screen + Orange light fades off >few seconds> Nokia screen fades off.