Follow-Up:
The comments/replies posted here are all well understood. I was under the impression I had bought the radio from an "authorized dealer". On the bright side, this story now has a positive ending.

Although the Ebay seller had nothing but Radioddity products for sale and their seller name was 'radioddity', they were likely just a seller that misrepresented themselves as being an authorized dealer. I can't be sure now since they're long gone and can't be checked. At the time of purchase the actual Radioddity website store was out of stock and didn't have any GD-77s to sell. The purchase went without incident and I've enjoyed the radio until it died, knowing it was a cheap entry into DMR.
In the meantime, knowing I had nothing to lose with a dead radio and seemingly no support, troubleshooting the dead radio revealed that the internal SMD 3A fuse was open, a minor repair. Problem solved. It's now working again.
Now several days after the fact, Radioddity has offered to replace the failed radio so in fairness I must give them the nod for (finally) standing behind their product.
Now another Latin phrase comes into play, "Mea Culpa", however the 'Caveat Emptor' phrase I used earlier still applies to me as well as anyone else reading this. Verify and validate that a reseller is authentic by vetting them before committing to any purchase.

73 - de N6PRX
P.S. I'm still a bit puzzled... here is the final response from Radioddity support:
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I am sorry that you cannot reach out to the seller via eBay. After confirming with our team, we could check your order record successfully. And Radioddity values you, we would love to help you return the defective radio and exchange a new one for you. Would this solution could be acceptable?
If acceptable, please feel free to let me know, and we will send you the return instructions to help you return the parcel. Many thanks for your kind understanding.
Cheers,
[name snipped]
Radioddity Customer Service
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