Apple TV 4K won't go to main menu after software update to tvos 13.4

I have 2 Apple TV's (both 4K). I just updated both units to tvos 13.4 (from an os in the 12's).

They both came back with a white screen after the update. The only button which works is the search button (on the iPhone remote app, there isn't one on the hard remote). From there I can find the underlying products (apps, movies etc) and they work, but the menu key won't take me back to the main menu. I have reset both boxes with the remote and by unplugging both units, but they come back the same way. I cannot get to the settings app (the search function doesn't find it) to reset the boxes that way.

I cannot seem to find a similar problem elsewhere.