My Synology NAS will not power on. How can I check the power supply safely?

Applies to: DiskStation models with an external power adapter. RackStation and internal-PSU models need their own hardware procedure.

Work through these checks

1. Record whether the power LED is off, flashing or steady, and whether the fans start. Photograph the NAS and adapter model labels. Stop if there is a burning smell, liquid damage or damaged wiring.
2. Check the wall socket and firmly reseat the AC lead and DC connector with the equipment safely powered down. Avoid repeated power cycling of a NAS that is still booting or rebuilding.
3. Observe the external adapter's indicator, if fitted. An indicator changing when the NAS is connected is useful evidence, but does not by itself prove whether the adapter or NAS has failed.
4. Use only a Synology-approved replacement with the exact compatible model, connector and electrical ratings. A plug that fits is not sufficient. Ask for assessment if a known-compatible power supply is unavailable.

Confirm the result

A successful power test should lead to a normal boot and access to DSM. If power returns but the storage pool is degraded, handle that as a separate storage incident.

If you need help

Include these details in your ticket: NAS/adapter models, LED sequence, recent power events and a short video of the start attempt.

Updated 261107