I have a Dell Latitude E5440 that's been running fine for several months.  Now when I boot, I get the following:

1) Screen comes on

2) Dell logo pops up

3) Screen goes black... blinking cursor in top left of the screen

If I hit F2, F12, or hold FN on power on, I'll get the message of entering setup, entering one time boot menu, or starting diagnostics respectively.  However, the system immediately goes to the blinking cursor and never enters theBIOS, one time boot menu, or diags.

Things I've tried to fix the problem:

1) reseated the memory

2) disconnected the CMOS battery (and AC power, removed battery and pressed power for 10 seconds)

3) booting from CD, DVD, USB, etc. (inserting the various media in the computer)

All to no avail.

So now you're thinking, what happened right before this all started? On Friday I tried booting from a USB drive and couldn't get it to work.  I changed the boot order and put EFI USB before hard drive.  It didn't fix the problem so I stopped trying and put everything away.  When I tried using the laptop on Saturday morning, this issue popped up.

This is a Linux only laptop.. No dual boot, no buggy Windows.  Please don't ask me if I can boot into Safe Mode. Even if I did have windows, the laptop never turns over to the OS.

Any ideas?