In its former, pre-burnt-out life, was this thing a capacitor?
It almost certainly was an MOV, Metal Oxide Varistor, a type of transient suppressor.  It is on the AC side of a bridge rectifier, next to wires marked Line and Neutral, and next to an AC-rated film capacitor (the yellow box) that is part of the power line input noise filter.  All of this points to primary-side protection.

In the center photo, the signal path is from the input wires, left through the fuse, up to the first layer of capacitors (both line-to-line and line-to-earth), right through common mode choke L1, then through another layer of capacitors, then down through the bridge rectifier.

If the supply is a universal-input type, then the MOV is rated for something in the 270-300 Vac range.  The physical size determines how large a transient it can absorb.  You can get approximately the same protection by matching its diameter.