Here is a photo of an Xbox motherboard that I received as a failed mod attempt. Prior to fixing the traces the box would attempt to boot three times and then go to the flashing red and green led. The orange line in the upper center is where a conductive pen was used to attempt to re-connect a lifted trace.
NOTE: Always use a 15-20 Watt soldering iron for work on a motherboard. You can pick one up for $7.00 at Radio Shack. I cannot stress this enough, if you think it can be done with a 30-40 watt iron you are making a $200.00 mistake. Sadly this happens way too often and it can all be prevented for $7.00.
Also, not so obvious is that the pad above it was lifted and is not connected.
to resolve this problem the goal is to reconnect both the originating point an the terminating point with a length of wire. Cut 30AWG insulated wire (buy it here) to length as appropriate, strip and tin the ends.
As you can see the lower blue one is tough to get at, without heating up the orange component with the iron.
Using a 15-20 Watt soldering iron, tin the points and the ends of the wires with solder. All you need to do is make contact, don't focus on getting a large amount of solder, a wire that stays in place is all you need there will never be any stress on the wires and it is not a race, take your time. Use an X-Acto knife to scrape off any green board material away from the solder points. For this fix I needed to solder two wires, I started with the hardest one first (the blue one), I spent about 20 minutes trying to attach to the trace itself and gave up and decided to try to solder at the termination point next to the orange component you see in the pics. This took about another 20 minutes to get a good connection. The second wire is easily accessible and took less than 30 seconds to complete.
I did not get a finished pic, I didn't expect the first wire to be connected properly so I assumed I would be re-assembling, what do you know it boots up with no problems!