Disconnect the AC adapter and remove or disconnect the battery. Hold the power button for 30 seconds and remove the base cover. Remove and reinstall both memory modules.
Verify that the LED on the AC adapter or DC plug is ON before you plug in the notebook end. Plug it into the notebook without the battery. Does the AC adapter LED stay on?
No --> there's a short circuit in the system; the DC jack or mainboard is bad.
Yes --> try powering up the system. If it will with the battery removed but not with the battery installed, the battery is bad and will need to be replaced.
Still no sign of life after the above? The mainboard is bad and will need to be replaced.
If you need further information please post the full model number (i.e., Inspiron N5110, 5523, etc.).