I have the same problem ~ also hadn't used the camera much before this happened. When i long press the power button the display screen shows its start up image for maybe half a second before going black ~ i'm guessing it could possibly be a battery problem? Replacement Batteries seem to be around £10 on ebay ... another link here: http://www.digi-quick.co.uk/alba-d31h-battery
Some Consolation > If you connect the USB out on the camera to the USB in on your computer with the appropriate cable the RED circle light is displayed around the video button at the top ~ if you then press the PLAY> button which is above the headphone socket this circle light will turn GREEN~ now your computer will 'see' the cam which can still be used as a webcam as long as it remains connected by choosing it in whatever cam application you're using ...
Infowars Dot Com, January 2014