RadWagon Power Issue - HELP - I've tried everything


I have a 2020 RagWagon (w/ the larger wheels).
For background: The bike has 3,000mi on her. I'm a pretty good mechanic and keep my bikes in good shape. It's never been wrecked and has generally been dry and kept in a climate controlled, covered environment.

A number of months ago I rode to see Bruce Springsteen. On the way back the bike started dropping power. (apparently, baby, I wasn't born to run). Everything works as normal, but as the power kicks in, the power seems to ramp up to the expected level and then drops completely. I can even see on the display where the wattage runs up to a few hundred watts then drops to zero. This happens at all PAS levels and is identical when using or not using the throttle. I can get power back by turning the unit off/on. Pedaling backwards seems to work sometimes, as well as just waiting for a bit (20-30secs?), sometimes. However, any power recovery just sees the issue repeating itself right away.

I'll keep this post strictly to solving the mechanical problems, rather than complain about recent RAD parts and service. I just really want to get this fixed and I'm all out of options, and like Air Supply said, I'm all out of love.

Here's what I have done (in the order I recall):
  • General maintenance and inspecting connections and wires (issue repeats)
  • Inspect crank (issue repeats)
  • Unplug and isolate brake sensor cables (issue repeats)
  • Replaced fuses in battery (issue repeats)
  • Borrowed a RAD battery from a friend to test the battery itself (issue repeats)
  • Ordered and installed a new controller from RAD (issue repeats)
  • Ordered and installed a full rear wheel assembly from RAD (issue repeats)
  • Ordered and installed a battery tray from RAD (issue repeats)
  • Ordered and installed new wiring harness from RAD (issue repeats)
Like I said earlier - after each 'fix', the issue is EXACTLY the same. I. have not been able to tell any difference in the problem at all. It's exactly the same issue, over and over.
At this point it seems like I've replaced everything but the LCD head unit, which would seem to me to just be a 'dumb' display rather than controlling anything?
I live in Austin TX, and there are no longer dealers on service centers locally.

Anyone have advice? I really do love this bike and want to get it running correctly again. I was able to return the wheel/motor assembly to RAD, but other than that...I've paid to replace damn near the whole damn bike and it still isn't running.

Help me Obi-Wan...you're my only hope.
You have comprehensively replaced everything except one thing. You even replaced the wires. That one thing left is almost certainly your problem, provided you didn't introduce some confounding factor in by switching something back during your step by step replacements.

Displays do contain more than just switch function. I'll give you one example: I was recently working with a pair of new DM40 displays on two separate bikes powered by Bafang BBSHDs. I wanted their 9-level PAS support, and I got it for a couple weeks. And then, after a couple weeks of proper operation, I started noticing after I'd click up to PAS4, I'd get a big power drop. From PAS4 to 9 I would then go from zero to higher levels of assist, but very small ones. I eventually confirmed it was the display (swapping in an 860C to confirm it wasn't the motor controller). Then I installed the same model display (physical display came from a different seller, and its production batch was a fwew months' different) on an otherwise identical second bike. For a couple weeks it worked as expected. Then it too became wonky in exactly the same fashion.

When I reinstalled the displays and set them for 5 levels of PAS, they both worked perfectly forever.

So... a display is not just a dumb switch that accesses brainpower resident in the controller. Its got some built into itself.
The display generally has a speed limit built into it. The units should max out at the speed limit or cut assist. If they shut off like yours is doing, that's probably a malfunction.