This looks like it might be the issue here. If you have the amp set up for bridge/mono then the L+ amp output will have the positive waveform on it and the R+ will have the inverted waveform. If you then have the positive of one sub voice coil attached to the amp L+ and the other voice coil positive attached to the amp R+ then you've set the sub voice coils up to cancel each other. We've had a number of conversations where I work (work is slow at the moment) and we really don't see why this would cause the amp to blow. Maybe others can shed some light.

A typical correct setup for the sub/bridged amp would have only two wires going to your amp from the sub: Positive on the sub going to L+ on the amp and negative on the sub going to R+ on the amp. The two voice coils on the sub can be connected in series or parallel. Choose which ever configuration your sub and amp support. Your amp will drive between a 4-8 Ohm load. So if your voice coils are 4 ohms each hook them in series. If your voice coils are 8 ohms each hook them in parallel. (I looked but couldn't find the info on your sub.)