TRX 300 FW stopped while idling yesterday. Blown fuse which blew on replacement.

Today I rigged a testing light to the fuse and found that the CDI box is blowing the 20amp fuse. I even disconnected the power to the box and it still has a short with just the one square plug connected.

I tested each wire in the plug and found the black with silver bloches is the culprit. This joins to three other wires, one going back towards the battery and the other two go towards the handle bars. Disconnected the last two … no change. Having trouble finding where the one going back to the rear goes, can’t see it exiting anywhere and I’m reluctant to start unwrapping the main harness.

Question:
Do these symptoms sound like a faulty CDI box. If not what might be going on?

Thanks in advance, any help greatly appreciated.