Laptop troubleshooting forum: HP Compaq nc6220 won't turn on/boot up

Hi if anyone can help me here, i would be extremely grateful. I have already tried the reset procedure you recommend i.e. unplug, remove battery, hold power on button, etc. and that didn't work!

three days ago, my HP compaq nc6220 worked perfectly, now it doesn't! there doesn't seem to be any reason. the battery had run out when I last used it, so when I went to use it last night, I plugged in the AC charger and the light showing electrical connection lit up in orange. I then pressed the "on" button. The green lights lit up which is normal. However, after about 5 seconds they turned off.

does anyone know of any other reason why this may have happened?

One thing I've noticed is a little hole in the side of the laptop not far from the "power on" button, that has a picture of a padlock with a "k" above it. Is there any chance that this padlock has been turned on? (although I have no idea how this may have happened)and if so, would this stop the laptop being powered up?

Once again, any advice gratefully received!

Cheers
Jules