I have an Inspiron 3542 laptop that I just upgraded to Windows 10. The update completed but now the device is saying Windows 10 needs to be activated. The error message reads: "Activation failed because this device doesn't have a valid digital entitlement or product key. Error code: 0x803f7001". This is a Windows 7 Pro device purchased from Dell in 2014. I tried calling the help line but they bumped me over to a fee for service help line because I am out of warranty. If they sold me a device with an invalid key shouldn't that be on them to correct regardless?
Is there a simple fix to this. It was activated and running fine before this upgrade attempt. Should I just revert it to 7 Pro and leave it alone?