Saw your picture in the other forum, This is between the display and the controller?
Which side was damaged the most? Cable coming out of controller or harness toward the handlebars? The harness branches out to probably a 5 pin plug for display, 2/3 pin for brakes, and a 3 pin for thrrottte.
The fact that the display powers up means it is getting battery power and ground. THe display can power up with a dead controller. WHen I said 5 pins in the display, those are two of them. A third will be a start wire going back to controller. It will be zero and go to battery power when the display comes on. That is what turns on the controller. The other two are serial data lines, in and out. Error 30 ("communication error") means the display cannot find any data on its incoming line. Could be one of the data lines is broke, or the controller never powered up.
If you unplug the throttle, you can probe for +5V across two of the three pins after the display lights up. If there's no power there, the controller didn't power up.
You can also have fun opening the controller (no battery connected!) and mapping the 10 signals from inside the controller to the round connector in your picture. Then you can do the same for the harness pins for to its peripheral connectors. Finally connect the harness and check continuity all the way out to the four plugs on the end of the harness. You don't need to know it works to do that and it will tell you if the wiring is good.
I've never seen a Rad product up close, but have seen about a half dozen controllers/displays and they are as I described here.
