Can confirm.
Last time i put a perun in an mp5 (cyma gearbox), i found the ICS stickers to be the key
Mp5 are a little more finnicky with testing for the perun
I would suggest assembling the gearbox in the lower, with only the trigger, sector gear and mosfet in the shell
(as per Perun's own advice) >
manual
From there, connect the battery with the gun on safe and the mosfet should go into "debug/test" mode.
Go through your fire selections.
Flashing yellow means motor disconnected (which, yes, it should be for this part)
white- safe
blue - semi
red - auto
purple - trigger pull detected
green - sector gear movement detected
from there you should be able to tell if the sensor sticker is properly aligned
if it is, then great, put all the other bits back in and fully reassemble