If the laptop boots up and connect to the Internet, use the Quick Test tool in the support section at Dell.com to diagnose many common problems. If it does not boot up normally, repeatedly press the F5 key after powering up the unit to bring up a boot menu, then select the Safe Mode With Networking option. This often allows the computer to boot up and connect to the Internet so that a Quick Test can be performed.
If the computer does not boot up even in safe mode, select Advanced Options from the boot menu to access diagnostic features available with some models. On other Dell models, access diagnostic features by pressing the F2 key after powering up the unit. If diagnostic tests confirm that the hardware is functioning correctly, consider restoring the system software.
If the laptop does not power up, try a different wall outlet and check the connections along the external power cord and adaptor to ensure they are tight. If the laptop does not power up using the battery or an external power adaptor, the issue is most likely defective hardware requiring a repair or replacement of an internal component. Check the unit's warranty status at Dell.com by providing the unit's service tag number, which is typically found on a sticker on the laptop.