Hi Graham, try this, enter the service menu by pressing install button followed by 4725 the menu will come up,scroll down to factory reset and press the button to the right of the OK button it will tell you to press the green button do so, the tv will reset itself and it should go into standby mode then press a channel button and tv should come on. If this does not work then you will probably have to change your power board (17pw20) v1, you will find this number on the right hand side of the board, pretty straight foward to change, you will find one on the net anywhere from £38 to £90, hope this helps regards Garry.
Garry
August 2010