My partner's micro USB port detached from the PCB as well. There were no obvious drops or stresses on the cable while charging, so I guess it is just a weak surface mount job. Before this she was always complaining that she had to plug it in several times before it would charge.

I'm in the process of attempting to resolder it to the PCB, but so far it hasn't been successful. The working space is extremely tight, and I had to file my soldering iron tip down to a flat shape to get access to the pins. My next step will be to remove the connector completely, apply some new solder to the PCB, and try to solder it back on.

This teardown video of the N900 from YouTube was pretty helpful and the device is amazingly easy to take apart:

http://www.youtube.com/watch?v=aVEHm325-z8

Since I have an N810, we're still able to charge it thanks to similar battery pins:

http://thpmaemo.blogspot.com/2009/12...y-in-n810.html

But of course it's not possible to flash new firmware.