You may want to try a static discharge . Try removing the battery and the power supply . Once there is no power available to the machine hold down the power button for 60 seconds. this drains any residual power from the board and allows the machine to boot normally . If this brings no joy try removing one stick of ram from the machine and try booting then switch to the other stick . often when one stick of ram goes bad you get the conditions you describe. if none of this helps then you need to start looking at the display or the video controller