What you've ordered, is sole PCB, without even SoC on it... Unless you own mini factory, You won't be able to re-solder everything to it Also, You've damaged element on PCB, not PCB itself.

As for damaged "something" between USB port and chip itself - if establishing USB connection directly via testpads would prove itself doable - it will require tracing down exact damaged component (if shorting fuse pads doesn't help - and if You've made it correctly, not "cold" solder - You've probably just destroyed another working component, fuse), then replacing it.

It;s something I would not try without correct equipment (how do you want to check every small element between port and chip - you may test resistors etc, but do you know meaning of *all* element, to test them correctly?), even given the fact that I feel comfortable with soldering small things.

If You can't find repair centre in Your place, find it more far away. It's probably only one thing You can do now, instead of dealing even more damage to Your N900.

As last resort, You may sell it - stating that USB isn't working and it's not cause of broken USB port, but serious motherboard damage - add some $$$ and buy new one. It may result in same ammount of additional money needed, that repairing motherboard in repair center.

Sorry, but if it's not a fuse, I think no one here will be able to help You.