Thanks for the update.
If they built the computer from the beginning, did they activate it, or did you purchase a license key separately? What Windows edition is currently running on your computer? Is it the same as previouse edition before performing a clean install?
Please click Start > Type winver and hit enter> Screenshot and post it back.
Also, go to Settings > Activation > Troubleshoot > What error code do you see? Send a screenshot along with the provided slmgr command.