Cannot open App Store - shows white screen

I have a brand-new Apple TV (4th generation with Siri remote, 64 GB). Everything used to work as expected for about three days – until yesterday.

I loaded a game from the App Store (which worked), but since then the App Store no longer launches. I always get a white screen. On the home screen, pointing at App Store used to show previews of apps. No longer; now the top part of the screen shows a big app logo on a blue background.

I already tried many suggestions that I found on various web sites: Unplugging, quitting apps, restarting, complete reset, log out from my account, log in again, resetting again, doing a manual setup, switching network. Nothing worked.

The wireless network apparently works. At least, I can view my photos from iCloud, and I can access the iTunes libraries on my other computers from the Apple TV.

Now I am at my wits end. Without being able to load any apps, the Apple TV is pretty useless…

Any pointers to solutions are highly appreciated.

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