Windows activation lost after motherboard replacement

First check whether this is really an activation problem. Open Settings > System > Activation and note the activation status, Windows edition and error code. Also run winver.

An “Evaluation copy” watermark often means that an Insider Preview or evaluation edition was installed, not simply that activation was lost. If the repair shop installed a different edition, such as Enterprise or Insider Preview, the original Home or Pro license will not activate it.

If the installed edition is correct, try:

1. Sign in with the Microsoft account previously linked to the laptop.
2. Open Settings > System > Activation > Troubleshoot.
3. Select I changed hardware on this device recently.
4. Choose the old laptop from the device list and select Activate.

The original preinstalled OEM key was normally stored in the old motherboard’s firmware. Check whether the replacement board contains a key by opening PowerShell and running:

(Get-CimInstance -ClassName SoftwareLicensingService).OA3xOriginalProductKey

Do not share the displayed key publicly. If the command returns nothing, the replacement motherboard may not have been programmed with the correct OEM key.

For a motherboard replaced under warranty or by an authorised Lenovo repair centre, contact Lenovo and ask them to correct the Windows key in the replacement board’s firmware. If the wrong Windows edition was installed, back up your files and reinstall the original Home or Pro edition. Once the correct edition detects the firmware key, it should activate automatically when connected to the internet.