My dell D810 won't power up. After pushing the power button, one LED light comes on. About 5 seconds later, that LED light goes off. I swapped power adapters and symptoms remain the same. The battery is fully charged (based on the battery's LED test button. 5 LED's light when the test button is pushed). Thanks.

Please try the following troubleshooting steps:

1 Disconnect the battery and the charger
2 Let it sit for 1-2 minutes.
3 Press and hold down the power button for 30 seconds.
4 Connect the charger (don't connect the battery yet) and try to start by pressing the power button.


Let me know if everything remain same.

Try this things first, while the computer is off press and hold the power button and fn key, make sure adapter is plugged in properly and the battery, if it still won't turn on try to use a known good battery,
but I'm gonna tell you since you already tried to use another adapter, if your sure that the adapter that you used is working good, then you'll need to replace the motherboard of that computer.

Hope this helps!

Had same problem with my laptop but it would work okay a week or month later for several on/off power cycles and then return to the same old problem "button not responding" problem.

TOTALLY disassembled it down to the motherboard and found green fungus/mold had eaten some of the smaller parts and connections.

Hope this is not your problem.