Z axis suddently bug

Yesterday my printer worked fine, today the z axis doesn’t work, i check all wire, no problem, mechanical problem, nothing, microswitch , no problem ,voltage on driver , problem : the voltage do down or go up ( without usb connection ) , the voltage is not stable, i try the z axis motor on other working pin ( x axis ) , the motor have the same problem
he does’nt start , or he start in bad direction , or when in move , i suddently change direction. i think the motor is dead and the board is dead too ( i change the driver with a working driver , problem persist ). Today i call my seller located at Le Havre in France ( Sonokit ) , i give me a new board, and a new motor, i reinstall the defectives parts and the problem persist… the voltage is ok for the drivers , the problem persist even without z axis ( motor axis free ) : shake , change direction, not start…
Can you help me with new point of view ?

Thanks in advance.

The problem is simple, default on motor wire ( original wire ) , i cut 1cm of motor wire and the problem was fixed.
the more strange is the problem appear after 1 month after building, i don’t understand ( broken with vibration ? ).
if i mount a new printer , i will use wago for testing motor.