You could take the doors off, kids do learn not to touch things, eventually. They are only buttons etc, they really can't do much damage to anything. Another possibility would be a cooling fan mounted to the cabinet to move some air out of the cabinet. My Denon is in the open so I can't really comment, it just gets a little warm.

Jason
M80 v2
VP160 v3
QS8 v2
PB13 Ultra
Denon 3808
Samsung 85" Q70