Ran into a problem with my Lenovo T400. The laptop would not power on. No lights of any kind. Tried with and without the battery and/or AC adapter. Found these instructions while searching around for a solution:
- Ensure nothing is plugged into the computer
- Remove the battery
- Press power button 10 times
- Press power button down for 30 seconds
- Press power button twice
- Attach ac adapter
- Press power button once. PC should come up. Perform normal start up. Everything should be fine.
- Shut down and reinstall the battery
Worked like a charm.