Describe what happens after power-on
No lights, fans with no picture and a boot error are different symptoms. Record sounds, lights and exact messages. Do not assume all three mean the power supply has failed.
Check accessible external connections
If safe, check the outlet, power lead, monitor input and model-approved charger. Remove unnecessary external accessories. Stop using visibly damaged leads or equipment with heat, smoke or electrical smells.
Avoid destructive recovery guesses
Startup repair, reinstalling and resetting have different effects. Check backup and recovery-key availability before choosing recovery options. A screen message or repeated restart should be recorded before changing settings.
Escalate with useful information
Share the model, recent changes and whether files are backed up. Internal work should follow service instructions. Never open a power supply, and do not promise a diagnosis from one indicator light.
Questions about this guide
How can I describe a computer that will not start?
Say whether lights, fans or sounds appear and whether the screen shows anything. Distinguish no power from a machine that powers on but cannot load its operating system.
When should I stop trying to switch it on?
Stop if there is liquid damage, smoke, an electrical smell or visible battery swelling. Disconnect power when safe and seek appropriate hands-on advice.