2005 club car DS no longer works after light wiring mishap

[Murph56789]

So the golf cart in question is a 2005 club car ds. Worked for the past couple years fine, although randomly slower and louder at times. We wired in a led light kit from golfcartgarage and one of the connections was incorrect. Once all connected we reconnected the batteries and flipped the tow/run switch to run. It made a slight unfamiliar noise. Then I turned the key and there was a loud pop followed by smoke. We disconnected all new light wiring for now (will address that next), and now there is no power or clicks from the golf cart at all. The battery voltage gauge and low power light no longer come on either. Its completely dead. The questionable wiring was to the back of the key and the voltage reducer, separately. Is it possible the key switch got fried? The battery gauge shows a slight light with the key off now, and nothing with the key on. Also, I’m assuming we fried at least what was smoking. It was a gray box with the main battery wire coming out that goes to the first battery on the drivers side. Maybe a controller or computer? Ran out of time earlier, need to do some more digging and research.
Also, we were planning on doing a speed upgrade to this golf cart and if a speed upgrade replaces parts that were damaged that is a win win. So first, anyone have any insight on what we could have damaged? And second, any speed upgrade recommendations for this particular cart? Was thinking of upgrading more than just the motor for more speed. I will try to attach pictures of the gray box that popped and was smoking..

[Murph56789]

Pictures