The hatch from the cabin to the MEC on our aircraft has been screwed shut now for a few years. The pilots know how to open it. It is to stop a passenger getting in there.
But now we have been told not to use the hatch at all after a cabin crew fell down an open hatch and landed on the engineer! All access to the MEC will be via the outside door.
I cannot think of any reason for a pilot to enter the MEC on an A320. I work on A320 every day on the line as an engineer, and enter the MEC once every six months. We do not rerack computors today. We cycle CBs.