First you need to remove the back cover. Just the back cover. (This is a nice tutorial https://www.youtube.com/watch?v=kDsZLl_JzwA )
Second. Locate ITEM #1 at the top of the phone shown in the attached pictures. This is a copper metal tab that bends easily. My guess, this get bent during teardown.
Third. Locate ITEM #2 on the back cover shown in the attached pictures. This is a contact point for ITEM #1.
Fourth. Bend ITEM #1 so it contacts ITEM #2 when you reassemble the back cover. That's it.
Fifth. Download GPS Statues from the market and test your GPS.
Sixth. Hit the thanks button and enjoy a beer.