bizhub c300 displays steadily "Now warming-up" and stops starting up?!?

[MM-Bürotronik]

Hello,

bizhub c300 displays steadily "Now warming-up" and stops starting up?!?
Has anybody an idea what that could be?
What i've done already is: i changed the drums, belt, fixing unit.
In some forum i found something about the sensors of drums. maybe that these are polluted? i removed all the toner on the drums and the drum mounting support but nothing happened. still the same...

thank you

[Gaffers01]

It sounds like faulty NVRAM, run the KM NVRAM recovery tool and update to the latest firmware.