have you swapped motors from one side to the other?

there could be a short in the wiring somewhere which is causing it to constantly cycle between open and closed, but that is normally only the case when the bars are stuck, hence removing the motors to check them individually

on the rear motor loom you will see which wire it missing compared to the front loom so if you put a meter into this extra wire you should see if it's got power to it or not

when it has a pulse of power it triggers the motor to open/close and then this sends the signal around the rest of the system

what you may have is an older alarm which has been wired into the c/l loom which is not at fault

this is normally tapped into the circuit around the footwells, which is the next problem because there is so much loom stuck into such a small space

find the feed source for the trigger power first and see if thats constantly live and then get back to me, your next steps will be removing the sub-loom in the a pillars to check for broken wires there and then following it around the car under the dash