just repaired one it was a toughie here's what was done:
1. Followed the guide to opening the case
2. Removed the screws on the board and flipped it up to get underneath
3. found that the port was "perfectly broken"
"Perfectly" in that the USB port was off and the 5 pins was still intact.
now here was the issue, trying to solder all those pins on the board which couldn't touch and on top of that are extremely fine
but here's how i solved it i simply melted solder on the board, and swiped the solder iron on each point where the pins were to touch.
i placed the micro USB port on the board, placed my soldering iron on each tip long enough for the solder underneath to melt and amazingly it worked.
Pointers
1.Don't think that by soldering all the pins together it will work, it wont.
2.This is an arduous process if your not too skilled
3.Magnifiers go well with this
oh on pointer 1. when i say solder together i mean allowing the solder to "melt" on all of the pins