MX385 Radio removal

Hey everyone. I had a radio guy adjust my sidetone from the radio, and he
messed it up. No longer is the sidetone faint, it is now completely dead. My
question to the group is, what exactly do I need to remove the radio and
adjust the sidetone. I have a single hole in the lower center of the unit,
and need to know what is used to remove the radio from it's cage. A quick
reply would be greatly appreciated. I'm a little frustrated hiring
professional licensed people who cause harm to my plane. The radio guy has
vanished, and I need to just fix this myself. The radio is a Michel TKN
MX385 in a Cessna. The sidetone was faint, but working before it was
'adjusted'.

Regards,
Marty