Nx4 losing screen..its goes black

we own an NX4 , we randomly loose the control screen.
we had the problem a few years back. We first tought of an electricity stability problem so we added a UPS to make it all good and it seemed to work. But the problem re-appeared this years.

Everything else works, but suddenly the screen goes black. The only way to get the screen back is to power reset the board.

It’s very random it only happened 3 or 4 times this year wich is not a lot on a year of use.

anyone had similar problem?