Im attempting to fix my N900 today, I know absolutely nothing about this stuff. But the USB has been giving me trouble for about a month now, and It apears to have had some debri wedged in there at some time and forced one side of the USB port to become detatched from the main board. I followed the instructions on YouTube to take apart my N900 which was surprisingly easier than I thought, heres mine all apart
Now im going to attempt and solder both sides of the USB port to the board for more secure connection
If you buy an N900, the best way to prevent the USB from breaking is to file down the teeth on the end of the charger cable. I highly recommend doing this before taking it apart to solder. Although, once the USB breaks their is no sure way to get it fixed even under warranty. Nokia might not be able to fix it, they might not even try, I dont even think they have any spare parts for N900's laying around anymore. I found a company at palcocellphonerepair.com that is pretty legit and is reccomended by Nokia to repair out-of-warranty cellphones. They charge $82.00 USD to repair the USB on the N900, with and added $10.00 return shipping ($20.00 if you want to insure). They might not even be able to fix it, i called and spoke with them, they might send it back and refund all but $15.00 for diagnostics. Id rather just buy a new phone and solder the USB myself.
Just wanted to share this with anyone thinking of buying an N900, I think they are still the best and Im actually glad I took mine apart because now I can clean the inside and hopefully it will be like new!