inspiron 14z 5423 won't boot

Hi, my 14z 5423 when restarting is stuck on the dell splash screen.  i've been through numerous posts on this forum for the basic trouble shooting.  holding FN during power up does nothing.  if i tap F2 or F12 during power up, the F2 setup or the F12 boot options becomes highlighted, but i cannot select those options.

I have also taken the laptop apart far enough to verify all the cables are connected (keyboard, etc) and that the HDD is seated. 

the HDD light during power up, lights solid, then blinks twice, before freezing on the dell splash screen. please help.  thanks, jeff