  it was sent in for one repair 2 years ago,   Humm, did they replace the motherboard when it was repaired? If so, Dell might have forgotten to load the key and you may have this issue (follow steps in the below Article to fix it):  [URL]   Note that Windows will still download updates and work without activation, you might get some pop-ups, is it possible you were running without activation before? 
I have an Aurora R5 purchased directly from Dell that I wanted to restore.  Reading up it appears that the digital key is stored in the bios and I should have had no issues running the restore from a 16GB USB device.   All worked well until Windows was installed and would not activate.   At first boot I get "You don't have a valid digital license 0xC004C003".  The troubleshooter only tells me I can't activate and need to buy a license.   So I install updates per some MS KB articles and the message changes to "your hardware has changed recently".  and therefore can't validate.  Again, the activation troubleshooter and even signing in with MS account does nothing.  I am told to buy a genuine copy of Windows which I already did from Dell on this system. If I continue to update windows updates by installing the h20 update, the message then changes that I can't activate because I upgraded before activating and therefore must now buy Windows.  Again, the troubleshooter does nothing.   I tried using the tool to find the key on the system and it reported that the system is using a generic key that will need to be activated.   I also tried rearming with no success.   I have tried restoring the system 4 times, including redownloading the tools and making a new USB image.  Support wants $100 to assist which is just shy of the price of purchasing Windows again and quite frankly, this feels like an issue that should be dealt with warranty or not.  I'm actually being blocked from a license I have paid for.  I appreciate your time and any help you may have for how to activate Windows on this Dell system that I bought direct from Dell with preinstalled win10 home.  (and the recovery tools IS installing home, not pro).  
Aurora R5, Windows will not activate after Dell System Restore