I don't know with this later type as mine is older oblong shaped display. If their are screws at the bottom of the unit holding the cover down, you could remove it as their must be a seal between the two to be able to reseal it when you replace it . You'll be able to file it down then from the top with the cover and seal removed. If It's not removable you may be able to go at it (Very Carefully) with a junior hacksaw blade or a small nail file.
Good tip! Four allen bolts and four screws and it's apart. An emery board for nails has dealt with the aluminium burrs and smoothed off the wound. There's no seal between the two parts because the plastic part is actually totally closed in, the aluminium just forming the holding bracket. I'll let it dangle until tomorrow when my better half can visit a purveyor of nail varnish.