[Pavilion DM4-1165DX] Almost zero boot activity.

As the title says, I was given an HP DM4-1165DX that does not boot at all.

With the battery out, plugging in the AC adapter yields a steady white LED next to the power jack. Press the power button and the LED on the power button flashes for a split-second, then nothing. No beeps, no fans, no lights, no activity whatsoever. If you immediately press the power button again there's no LED flash, but if you wait about five seconds or so and press the power button again the LED will flash again, but still nothing.

With the battery in the same thing happens, except the LED next to the power jack flashes. HP says this is a symptom of a battery that's reached its end of life.

Tried:

• Pulling/reseating memory
• Pulling the CMOS battery, letting it sit overnight
• Trying to boot without CMOS battery
• Different AC adapter (known good)
• Reset power manager (unplug, hold in power button for awhile, replug)
• Sacrificing a (box of) chicken (nuggets)

Any ideas?