Without opening this up like a can of worms keep in mind you don't need to register the kindle to do everything.
First off you can use calibre to download free web content and convert book formats (epub, lit, pdf, pdb etc)
If you can't use calibre well maybe this might work...
Just put Doukan on it
You'll be able to read epubs and there's a fair amount of them around as that's what other readers use.
Around 16 years ago I found a half broken Coleco Adam at a recycling center and tried to use it. It could load..kinda..graphics were all screwed up but eventually I realized it was a lost cause.
A company usually isn't going to support a product if it went though a 3rd party that might have been a discounter. I worked for a box retailer for years and old "resets" (it means old displays and material often times new product is the same but different packaging) would be sold to discounters. Should this product be able to be returned back? Probably not.. ever read the policies for returning items at a store these days? it goes on for nearly a page...