I had the same problem sent it away to Nikon who couldn’t fault it,,so,,,,,,,
remove the four lcd retaining screws so you can get in and behind the screen there you will find a small electrical connector ( silver in colour and slides onto the circuit board and clips into place)and a larger connector,,I found that the larger connector purely by chance wasn’t located and clipped securely in place,,you’ll see what I mean once it’s opened up…
resecured and everything worked as it should reattached lcd screen ,,,never had an issue since