I purchased a RadCity 5 last year and it was also DOA. Was able to connect with tech support (on the Weekend) and we determined that it was the controller. They placed the order and it took a couple of frustrating months to arrive. I installed the new controller and the bike has been a pleasure to ride ever since. To my Suprise a few weeks later another controller showed up so I now (hopefully) have a spare...

• The current working controller is manufactured in China.
  Original controller and spare are from Vietnam.

My suggestion is to enjoy the bike while waiting for the replacement controller...(builds muscles and eases stress...)

After 6 weeks and 120 manual miles the controller finally arrived. What a difference and pleasure to ride. The attached photo below has the old and new controller. The new one is made in China and has a green dot.
Very straight forward replacement procedure (maybe 1 hr) which gets you familiar with the bike electronics.

Yes, I was very frustrated after spending a bunch of money on the bike, putting it together and found that it didn't have any power assist... The support staff was pleasant, did their jobs (on a Saturday 7/2/22) and ordered the part. They even set the correct expectation that it would be early August for the part. 

It's a high-tech bike, you'll need some electro-mechanical skills to keep it going, things are going to happen (everything breaks!).   

Enjoy 
 

Please let us know if the controller replacement was successful. I'm still waiting for my replacement controller ordered on 7/2/22. The harness is on the way but I'll wait until both are here for the replacement. I did a trial run and removed the controller (see attached Photo).
Made in Vietnam, Revision:I, Hopefully you received a different version.

Found that the top battery bracket (with lock) was broken and added this to my service ticket. Haven't heard back. They must be swamped...

B.T.W. have been riding the bike the old fashion way (100% manual) and enjoy it. Get lots of positive comments on the look of the bike.

Just received a RadCity 5 Plus today spent the afternoon putting it together and minor adjustments. Put the battery in turned it on everything looked great, went for a ride and noticed that the motor wasn't working. No throttle, no petal assist.
Went thru the standard troubleshooting steps that others have posted on YouTube no help. Called customer support (They are working this holiday weekend!) They had me go thru the same diagnostic steps with the same results. They are sending out a controller and wire harness and I can improve my ebike mechanic skills.

Discussion Points
* I hope that RAD engineering understands the failure mode (if it does turn out to be the controller) and has implemented some
   corrective action into the "new" controller that will arrive.
*If there is a known bad batch of controllers in a range of bikes, update the stock of new bikes (I know it's expensive but so is a $2k bike for me...) or send updated controllers with the bikes.
*When it was released, it was priced at $1799.00. I paid $200.00 more, and it doesn't work... 
*Maybe this is why they are a direct-to-consumer company. Costco or Walmart would not put up with this reliability.

All of the reviews that I looked at are positive, it has the potential to be a great and popular ebike. I also love the look and features of the bike but... just in case, I've saved the packing material in case I need to take them up on the 14 day return policy.