Cetus Printer is blocked at to z axis

I got an older cetus from a friend.
Now he is blocked everytime I turn it on…
It makes strange noise and stayes in the top z axis.
Somehow I can not initialise it…
Any Ideas?
may a sensor crashed?

Many thanks

yes, check the Z switch at the top of the printer.

Yes I found a Video, the screw (end limitation) of the Z axis had to be tighten a bit…merciii