How to distinguish electrical startup, firmware initialization, boot-path, storage-detection, and display-output failures.
Separate no power, no POST, no boot, and no display before attempting a repair. They occur at different stages and require different evidence.
| Symptom | First checks |
|---|---|
| No power | Outlet, power cable, battery, PSU, and power connections |
| Powers on but does not complete POST | Recent hardware change, memory, CPU support, firmware, and board diagnostics |
| POST succeeds but operating system does not load | Boot order, storage detection, boot media, and operating-system path |
| System appears active but screen is blank | Monitor input, cable, display path, and graphics output |
Verify that a drive is detected before formatting, reinstalling an operating system, or assuming file-system damage. A black display does not prove that the system failed to start.