platform does not move upwards

New problem with the new M200.

It seems that the z-axis motor has lost its torque. 

It can move downwards when I give the order "move 5mm down", but when I select the opcion "move 5mm up", it doesn't move (unless I push up with my hand).

The platform is not blocked, since I can move it manually with M200 disconnected, and I can also turn manually the spindle with two fingers and any effort.

If I try autocalibration, it doesn't work. And It can also not print.

Probably it is related to this issue:

Probably it is related to this issue:

Im not shure, moving the platform up manualy ([Move platform 5mm UP]) does not stop even if the endstops reach. You can crash the platform into the nozzle easily

Thanks for your answer,

But I think that it is not problem of the 3-pin connector. It seems to be OK, and the behaviour of the platform is the same when the connector is disconnected. 

Before turning the M200 on this morning, I sprayed the aluminium plate with hairspray in order to fix adherence problems (according to several advices that I read in this forum). I have thought that the hairspray could have short-circuit any circuit in the platform. So I cleaned the plate with acetone, but the problem persisted. 

I think that exist the possibility that the coupling between the z-axis motor and the spindle is loose. A subtle buzz from the motor can be heard when I give the order do move up 5mm, so it makes me think that the motor is turning. But to check it I should disassemble the chassis and I am afraid that this would void the warranty...

The problem was solved replacing the motor. Our reseller did it quickly.