kernelpanic19

I have a Master Spa CS 738. It uses a Sloan X333205 - LED Daisy Chain Controller. Recently all the multi-color LEDs stopped working entirely. When I hit the Light button on the topside panel, I hear the relay click and I get 12V AC on the PCB where the LED controller connects. So I think the problem is the controller or the LEDs. I haven't found much info on the controller or LEDs other than the controller output is 12V DC. https://www.masterspaparts.com/controller-led-daisy-chain.html The controller connects to the LED wire via a 4 port plugin connector but I don't know which pins are which. I have no visibility to the LEDs beyond the wire lead coming out of the insulation. Any thoughts on troubleshooting steps? I'd love to isolate the issue to the controller because I am not sure if there are practical options to repair an LED issue due to lack of accessibility. Thanks!