laptop powers up but beep 8 times screen is grey then black

scot, 8 beeps is usually a LCD or cable failure. Try this first :

"If the LCD on the system does not show any display, here are some basic steps that you can perform:

Remove the battery and AC Adapter from the laptop and press the power button down for about 10-15 seconds to release flea power.

Power up the system and then press the F12 key during the boot process to get to the Boot Menu, if you are able to see the display.

It may be necessary to repeatedly press the key during the start-up process.

Use the up and down arrow keys to select <Diagnostics> on the menu and press the Enter key.

Or

Hold down the Fn (function) key

Power on the notebook

You should then see the Dell logo screen with the message 'Diagnostic boot selected' in the top corner.

You can then release the keys

While the LCD BIST test runs, the LCD is operating on its own, free of the video controller, which may be discrete (a video card) or on board (on the system board). The test allows you to distinguish an LCD panel problem from a problem with the controller. If the colors are displayed across the screen without a problem, then the issue is not with the LCD." from here. Should you have a broken LCD, then download the service manual from here. Page 41 will show you how to replace the LCD. Hope this helps, good luck.