and I wanted to put it on bottom shelf instead of a top shelf, so I combined two glass shelves into one

Bought this a year ago and when I got home last night I saw the bottom shelf holding the receiver shattered

You set the top shelf upside down on the floor - as you can see in the pictures there are four metal circles in the top glass.

The unit comes with four metal rods that screw into the bottom of the top shelf and extend through the middle if the columns