How do I replace the power jack?

All you have to do is first follow the teardown to get the back panel off. Don't need to even take the battery out (it may be safer for your hardware if you do - but I didn't). After that the power jack can be released by removing the screw, then lifting the clip and unhooking on the side opposite the screw hole. Then at the other end of the harness, the cable has a small plug which goes into the motherboard. The plug has 2 tabs, one on each of the short edges, while the wires go into one of the long edges. These tabs are held by small metal clips that need to be gently pushed out just a little as the plug is lifted. Gently slide a thin blade or screwdriver under the wires and a bit under the plug, and apply a little pressure to lift the plug. While you are lifting, use something small like a jewelers screwdriver (or the corner of a slightly larger slot screwdriver) to push out the clips on each tab, one at a time. The plug should come up a bit, then slide out (towards the wire side). Then install a new plug/jack/harness more or less by following these instructions in reverse.