I can't take a picture here, but the idea is that the meter mechanism is activated through a lever at the bottom of the bayonet whenever a lens is on the camera.
You can take a look at the M5's bayonet throat and play with the lever there a bit with a small screwdriver (carefully, of course). If you look at the adapter, it's easy to find out which lug it is that activates the lever - if you look at the adapter from the rear, it's the one opposite the center notch in the flange.
You have to file down the side of the lug which faces forward in the direction of rotation when you put the adapter on the camera - that is, if you look at the adapter from the rear and the lug in question is at the bottom, the right side.
You don't have to take much off, on my adapter it was maybe 2mm.
Bing! You're hypnotized!