"If the Meridian has philips for the top cover or allen screws, and can tell him the size of the screws, I would apreciate that"

I dont know the size but the very top cover is larger size Allen - four - one in each corner.

Then there is a second top plate, which has like 20 small bolts. I used a small flat blade screw driver to remove these.

The rear plate holding the IEC switch & filter combo is secured by 4 small Allen bolts.