I recently acquired a second hand Nokia 5800 XpressMusic mobile phone. Everything worked except the bluetooth. I just couldn’t enable it. There was a (quite common) error. Unable to perform bluetooth operation.
After fiddling with it for couple of hours I came to the conclusion that the error is due to hardware failure. So I striped the phone down and picked the main board (unfortunately I didn’t recorded the procedure). After that I located the bluetooth modules (info from the Internet). The only thing I could do was to heat them enough (reflow) in order to fix any bad connections (cold joints). No tools, no nothing at the place I was. So… I wrapped the main board with kitchen paper and cut a windows to expose the bluetooth module. After that I wrapped the main board with aluminium foil (aluminum foil for Yanks) and cut the same window. I placed the main board to a dish plate and placed it under a halogen spot light (a halogen spot light can easily melt solder paste). At first around 10 cm (4 inches) to preheat the board. After a while I moved the board directly under the spot light and left it there for ~5 minutes. After turned the spot light off I didn’t move the board for about 5 minutes. After it cooled down I reassembled the phone and the bluetooth now works for 3 days without errors.