K8400 z-axis not working

I’m having a problem with my K8400 3D-printer. The z-axis is only moving downwards. When starting a print, it moves all the way down (I guess this starts due to calibration), once down, it jams against the bottom of the printer and I have to stop it. When using control printer > move axis > z-axis, when I try moving it downwards, it moves downwards and shows a increasing z-coordinate on the screen. When trying to move it upwards, is also moves downwards and the screen shows a decreasing z-coordinate until it’s down to zero and it stops moving downwards. When trying to move it downwards again, the whole process starts again.
I already tried cleaning the end stop, but this didn’t help. I have had this problem several times before, but after restarting and resetting it several times, it would work again. But this doesn’t seem to help now either.
Does anyone know what the problem is? Can I fix it by replacing a certain component?

Thanks in advance.

-Niels

Swap components one by one to check, it’s like the 'dir’ection command is not given or not executed. I would check the endstop, this is one of the first thing who prevents to go up if activated, check the steppermotor and wiring, eventualy swap with components of other axis or extruder, so you have nothing to buy.

Yeah check the wiring, seems like something is not properly connected there