User Manual

• The laptop market is flooded with manufacturers and models, so it's safe to say that no two laptops are exactly alike. It's best to check your specific laptop's manual to see if your power indicator -- which might be on the power button itself, or on the side of the laptop -- has specific lights for troubleshooting. All laptop systems have troubleshooting light codes, but not all laptops use the power indicator as part of this. A flashing light might indicate, among other things, that the battery isn't seated correctly or that the memory needs to be reseated. Your laptop's manual will tell you the specifics for your system.
  
  

Power Indicator Light

• Again, since every laptop manufacturer builds its computers differently, it's difficult to take any single meaning from the power indicator light coming on. That said, a light of any kind on your laptop tells you that the motherboard is receiving power. Try unplugging the power cord and running the laptop on battery to see if the light remains on; if not, the battery may be the source of your problem. Check for other lights, too, like the Caps Lock indicator or a Wi-Fi light. If these lights are also on, the problem could be the screen.
  
  

Display Issues

• Laptops have different video output modes, and these modes have changed as computer technology has evolved. Older model laptops, from the early- to mid-2000s, may have connectors for traditional computer monitors while newer laptops may have a high-definition media interface connector. In either instance, the laptop will have display toggle button, usually a combination of the "Function" key and one of the "F" keys along the top of the computer. When all the lights are on, toggle between monitor modes to see if the screen had just been turned off. Alternatively, connect an external monitor to the laptop and see if you can get it to work with this different screen.
  
  

Clues from Sounds

• Listen to your computer. If the fan spins after turning on, then you know that power is going where it needs to go, at least in part. Beeps are also helpful when troubleshooting, since computer manufacturers program their laptops to beep as indications of specific problems. The support pages for your computer -- on the manufacturer's website -- should tell you what these beeps mean; if not, the technical support agents will know.