Dell e1705 won't boot

I have a Dell e1705 (with nvidia 7800 video) that will not boot. When I hit the power button, the power light comes on for about 5 seconds, then goes out. That's all I get. No sound comes from the machine - no fan, no HD spinning.
This occurs with or without the HD in place - I figured I might get to the BIOS at least.
This occurs on AC power (with and without the battery in the machine) and on battery power. When I try on AC power with the battery in, after the power light goes out, the battery light will blink once.
I tried various DIMM configs - both, just one, neither, no difference.
NONE of the other lights on the machine light up at all.
What to do? New motherboard? Something less drastic? Thanks in advance for your thoughts.

Steve
smichelsenAsked:
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liguruCommented:
My thought is the battery is no longer holding a charge and the AC plug is shot.  Does the light on the AC plug light up at all when plugged in to power? Not the light on the laptop itself, but the light on the rectangular box of the electrical plug.
 If not, try a new cord.
smichelsenAuthor Commented:
the AC power adaptor is OK.  The battery seems OK too as the power-tester on the battery lights up to show a full charge (5 out of 5 lights come on when the button on the battery is pressed.
 
nobusCommented:
disconnect disk,and cd drive; remove all ram
try to boot - it should beep.
if not, bad mobo or cpu.
if you like, you can try to reseat the cpu

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smichelsenAuthor Commented:
I reseated the CPU as best I could by pulling the keyboard, loosening the CPU via the locking screw on the CPU-mounting, and pushing down wherever the CPU could be seen through the framework and heatsink bar.
Put it back together, then pulled the HD, DVD drive, ram.  Tried to start - no beep.  Got the power light for 5 secs as before and NOTHING else.
nobusCommented:
then its a dead board..
smichelsenAuthor Commented:
ok thanks.  good thing Dell has a downloadable service manual1
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