Power button started working intermittently on this phone. Possible dry solder.
Main board needs to be removed to get at the solder connections for the power button. Disassemble as follows:
- remove rear cover;
- remove battery;
- remove sim card;
- remove 8 screws - note three of these screws are metal thread and the other 5 are coarser thread for plastic;
- remove plastic cover by gently prying around the edges;
- remove camera connector;
- remove microphone connector;
- main board is held in place with three clips, gently remove main board.
Sure enough, after disassembly a visual inspection of the power switch showed that the two contacts closest to the edge of the PCB had come away from their solder pads. Resoldering these fixed the problem.