I love that people stepped up to provide replacements but if you can’t get schematics it gets hard. I helped a friend do something similar on a system 80? Spider-Man where we couldn’t find schematics for the rotten dog.
I would start with the original WPC schematic and compare to the rotten dog if you can find it. Then see where the power from transformer comes in what fuses could be blown and what might be broken before the LED. In my experience the paths were the same the components were newer in some cases.
Here’s is a pic that will get you started. Once you figure out the input connectors and fuses go look at the schematic for the driver board for more info. Looking at this picture both 18V and 12V both come in from J101 pins 4 and 5 and F114. Start by testing that fuse F114 it is the common component
Let us know what you find
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