I was just having the same issue and it seems also due to having bought the reader in Poland. Frankly, I'm appalled. I'll never use the TTS and I only bought the thing in Poland because that's where I was at the time and it was cheaper to get it from a store directly
Is there any way to reformat the reader or do something to get rid of TTS and be able to update from here? Or is selling it and buying a new version from DE the only option?