I own an hp pavilion g6 computer and after awhile I would only be able to use it while it was charging . All of a sudden when I tried turning it on the screen would flash off and on. It won't let me log in or anything it just keeps flashing . On the corner it says "press esc for startup menu" . I thought it was my battery because it told me to replace my battery so I did. But it's still flashing on and off and I don't know what to do .