I know there are probably countless other threads on this but I still have no answers.  In 3/2013 I purchased a brand new Venue 11 Pro 7130 direct from Dell.  It shipped with Windows 8.1 pro.  I've never had any issues with it and it's never had any repairs done.  The other day I went ahead and did the free upgrade to Windows 10.  Everything went fine but I noticed that Windows was not activated.  When I try to activate I get the following error:

"Activation failed because this device doesn't have a valid digital entitlement or product key.  Error code:  0x803FA067"

I called Microsoft and they asked for my original product key.  I was able to pull the embedded Windows 8.1 key from the BIOS using the NIRSOFT key finder tool.  They said that product key was "blocked but still in tolerance" and they could do nothing to help me.  They said the only thing I can do is contact the manufacturer.  I'm well past warranty expiration on this unit.  How can this be a Dell problem?  Is there some recourse for me to actually use the "free" upgrade Microsoft is promising everyone who owns a genuine copy of Windows 7 or 8.1?

If not can anyone answer the question as far as how a product key gets into this state to begin with?  Does Dell flag ban product keys for the Windows 10 upgrade offer based on warranty status or something?