If you open the phone, you will find a SMC (surface mounted component) marked with K nearby the charge plug of the phone. This is a fuse, and if you get a new one, you can switch it, otherwise you can solder a small wire or something over it. But to be shure this is the cause of your problem, you measure the resistanse of the component with a multimeter. If it is 0 ohm, it is working, if it is more than 1 ohm, it is broken.
Cadmium, March 2006
