I have an Inspiron 1720. It will not power on with the power button. I have replaced the keyboard. I have verified the battery is good. I replaced the charger. If I hit the power button nothing happens. No lights, nothing. If I hit the Media button it powers up. If I interupt the Media Center pwoering up I can focrce the the laptop to startup Windows. (Vista O/S). Once windows is up and running I can not turn of the laptop with the power button. I must use the shutdown option. I read on another post that it might be the BIOS. I have updated the BIOS to the latest version from the Dell support site. Basicaily, everthing works except the power button for turning the laptop on and off. I tried removing the battery and disconnecting the power supply. I then held the power button down for about 30 seconds. according to anothe posting that should discharge a capacitor on the motherboard. that did nothing to help. I am at a loss.
I am assuming that you have the same system model. If you are facing the same issue as dgrinnan1 where you are unable to power on shut the computer down using the power button, then it might be an issue with the power button or the hinge cover.
You may try replacing the hinge cover first. Here is the part# KU971.