Around 15% of the Arduino Nano R4 I ordered for my courses were non-functional on arrival. When plugged in they performed the prebuilt routine, but would never appear as a device to the computer. For anyone else experiencing the same, it is easily fixed if you have access to a soldering iron.
Turned over, as you can see in the image below on the right side, is a large solder blob under one leg of the USB port.
This creates a short to ground for two different pins, rendering it unable to communicate via USB. Heating the solder with an iron can generally cause enough to flow back up the leg, that it can be cleaned even without wick.
I hope this helps someone else using these new boards!
Thanks for your report, and for taking the time to share the solution you found @jagerstenhaber!
I have notified the relevant parties at Arduino in regards to a general investigation of the problem. So it is not necessary for you to submit a ticket via the contact form for that purpose alone (though you are of course welcome to do so if you like).
It sounds like you were already able to resolve the problem on your own, but if you would like support with your order specifically, then the contact form is the appropriate way to reach Arduino customer service.
One would expect to see all 4 legs of the USB connector soldered to the PCB to ensure a stable mechanical bond so that the connector does not get ripped from the board. Obviously a blob like that is a quality issue. I would not have been surprised to see cheap clones from China with legs not soldered, but it is surprising to that on genuine Arduino board. Of course, it could be just the lighting in the photo or its soldered from the top and the solder has not flowed through. OP, out of curiosity, where did you buy these from?
I had a similar thing happen on a cheap USB charger board from Ali and didn't notice. The USB socket just ripped away when I tried to plug in the USB cable. I checked the other three boards in the pack and sure enough, none of them had solder on the shield pins. Fortunately in this case, I was able to make a repair as the tracks were not damaged. The pins just pulled away from the solder.
Our Arduino support team is currently investigating the issue closely. Although close attention and high quality builds are always part of our manufacturing process, mistakes may happen. For this reason we encourage all affected users to contact Arduino technical support directly so we can solve each situation individually. This will also help us identify the issue and prevent it for the future.
Thank you for your understanding and collaboration.
