Display Unit Goes Blank

I was preparing the aircraft for early morning departure and noticed the center upper DU goes blank. Aircaft is heading for Geneva and will fly back on the tonight.

I've reset the circuit breaker CB at P18 behind pilot seat nil joy, swapped it with lower center DU found defect transfered so confirmed the defect was the DU itself.

Check with Minimum Equipment List (MEL) found faulty lower DU is despatchable with cat C MEL.

My supervisor came onboard and double check the DU. He noticed a blink on the DU when he pull push the CB so he decided to do the ground test from FMC CDU maint page, walla.. sudddenly it come back to normal, so it is intermittent. However this is the sign that it gonna fail soon. So getting the spare in advance will be a good idea.