Computer Repair Technician how-to

How to Diagnose a Computer That Won’t Turn On

Start simple and narrow down the cause.

Updated By the Career Education Institute Curriculum Team
Quick answer

Start simple and narrow down the cause. In short: check; look; test, then complete the remaining steps below.

Step by step

  1. Check power cables, outlets and switches.

  2. Look for lights or fan movement.

  3. Test with a known-good power adapter or supply.

  4. Disconnect non-essential devices.

  5. Reseat RAM and check for beep codes.

  6. Test components one at a time.

Safety reminders for computer repair technicians

  • Use ESD protection when handling components
  • Unplug devices and discharge power supplies
  • Lift heavy printers and copiers properly
  • Protect customer data and privacy

Motherboard · SSD · RAM · BIOS/UEFI · POST · Malware: see the full computer repair technician glossary.

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