48v G29 burning up stereos. Can you troubleshoot?

[Kwick66]

Hello All,
New to the forum here.

I recently purchased a 2011 G29 48v with 6 new 8v Trojan batteries.
This cart already has a 48/12v reducer which was used to power the headlights/taillights.

I am trying to install a simple Amazon bluetooth stereo (https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1),
which I have previously done to my older 2009 G29 with 4 12v batteries, with success.

The first stereo that I tried to install, kept burning up the inline fuse. The second stereo powered up for about 5 seconds and is now not working- No fuses sacrificed, and no smell of a burned up unit.

Using the Positive and Negative 12 volt wires from the Reducer output, I've installed a fuse block with both Positive and Negative buss bars. Volt meter is showing that the + and - posts from the fuse block buss bars are producing 13.6 volts.

I've tied in some LED lights to this fuse block, and they work just fine.
Any ideas why the radios keep getting damaged?
Too much voltage, floating ground issues, reverse polarity, power through the ground...???

The radio has a small amp, that I had zip tied to the carts frame at rear shock tower. This exact same setup worked just fine in my previous 48v G29 cart which had 4-12v batteries.

I am stumped.