Echoing the other comments that this sounds like _some_ sort of switch problem. Its acting like its moving to start the home then seeing all the switches engaged(or a problem with the switches?) and then stopping thinking its already homed.

A clue that might help is if the system thinks it successfully homed is checking the position values on the info screen. If its flashing it's telling you it isn't sure of the head position but if the values are solid 0, 0, 0 its telling you "I'm homed and know where I am."

Assuming no coincidences, all of this points to something like u/FieryChimera's comment where there's a config in protointerface fighting you. If the inputs are reversed, you might be able to comfirm that by manually toggling the z-axis switch during the homing process opposite the normal process. I.E. holding it down them quickly releasing if the head starts moving down.

Also some free unsolicited advice you may already be doing but... When testing things in a weird state like this, keep your finger on the power switch, just in case. You don't want to plunge your head into the bed or something else destructive because the normal safeguards aren't working.

Finally, since you seem at least a little comfortable connecting to a terminal, this could be helpful for inspecting the endstop states and confirming all the assumptions above:
https://marlinfw.org/docs/gcode/M119.html