My power button does not work

Power button does not work, e-reader appears to work correctly once started via USB cable into a PC but no other method that I have seen put forward in various articles seems to work including multiple resets, pressing power button for 7, 15, 30 secs. disabling screensaver etc. Guessing this has to be a hardware problem, but if anyone had any other suggestions or options to try before I dismantle this great bit of kit, please let me know. Thanks