NVIDIA support not available in case of warranty

Had the tablet bought in November 2104 mainly because of the fast processor and the almost floor-Android-surface without much so-called "bloatware" and was with the performance especially in games very satisfied, the update to Android 5 came as promised very quickly.
Because of my opinion only average displays I got it but then the end of November on ebay sold privately and the buyer has contacted me a few days ago because the device could no longer turn on, ok.
But what did not work: the manufacturer NVIDIA agreed within the warranty period no jurisdiction !? Sorry, but that is only a flat of four stars. Amazon has it then ripped out and refunded the full purchase price to free return, one-time customer.