Windows activation lost after motherboard replacement

Replacing the motherboard changed the device identity that Windows activation uses, so the original digital license no longer matches automatically. First confirm that the installed edition is the same one supplied with the Yoga, such as Home or Pro. Open Settings > System > Activation > Troubleshoot, choose “I changed hardware on this device recently,” sign in with the Microsoft account previously linked to the license, select the laptop, and activate it. If you have the original 25-character key, use Change product key instead. Because the license came preinstalled, it is probably an OEM license rather than a transferable retail license. If Lenovo replaced the board under warranty and activation still fails, contact Lenovo with the repair record and serial number; the replacement board may need the correct firmware licensing marker. Microsoft activation support is the next step if the edition and ownership evidence are correct.