Power is on but the screen can not come

If you do not get a beep error, then there may be a problem with the display or graphics adapter. First, try connecting to an external monitor, if you do not have a monitor check with friends and family to see if you can use their monitor for testing. If you get the desktop on the external monitor then the problem is the laptop display. If the external monitor is also blank then it could be a bad graphics adapter or a bad mother board.

Another cause for this problem is power. Try removing the battery and turning it on with AC adapter, then try turning the computer with just the battery. If you do not see the Compaq/HP logo on start up then it is probably a defective mother board.