Well I didn't realize it was a laptop, when you boot try pushing the FN key and F7 if no response try FN &F8,then F9. You may also want to check to make sure the cable from the screen did not come undone, the battery bracket may be an issue as most of the time the - post of the battery connects to the motherboard through the clip.
Service Manual>
http://h10032.www1.hp.com/ctg/Manual/c00700903.pdf