Help! Dead 6610 Battery?

Hey all,

Here's the situation. I was listening to radio on my 6610 last night when I
fell asleep without turning the radio off. When I woke up the next day, my
phone had turned off, probably because the radio drained the battery (which
is likely since the battery was on one bar the last time I checked it). When
I went to charge my phone, the screen just stayed blank. I also tried to
turn on my phone whilst it was plugged into the powerpoint, and changing
powerpoints as well...still nothing. Finally, I pulled the battery out and
tried testing it with a little electric motor (from one of my brother's
toys), and found that the motor wouldn't run. I've left the phone plugged
into the charger for about half the day, hoping that it would start
charging, but so far it hasn't been successful.

So, my question is, did my battery just 'die' while I was sleeping, or could
there be another problem? The phone and battery (original genuine Nokia
battery) had been working fine up until now (my phone is just over a year
old), so I don't want to go out and buy a new battery to find that it's not
the problem.

While on the subject of batteries, is there any problem with buying
non-genuine replacements, or are they okay to use?

Any help would be appreciated.

Cheers,
Eminent