So I have this problem too. Device descriptor not recognized. I've tried Windows 10, 8, Ubuntu, the RCM Android App and SX Pro. Nothing works. Both RCM or normal mode, device descriptor failed.
A friend came over the other day with his switch. All my methods worked for him no problem. The same cables and everything worked for him and not me.
After weeks of trying everything I've come to the conclusion that it's hardware related. I've heard of people breaking something in the charging port or blowing a fuse related to the port.
Whatever it is, there is no fix for us unless we send it in for repair.
When a USB device is plugged into a port, it sends a device ID to the OS so the OS knows what it is, what drivers to load, etc.
My switch simply doesn't send an ID back to the OS. So no matter what I plug it into, I get the same results.
What I find interesting is that I can still dock it and play on my tv. The HDMI and charging still work.
I'm guessing the dock doesn't request the Device ID like everything else does.
I was hopeful that maybe the SX Pro doesn't bother with a Device ID check, but it doesn't work, so I'm guessing it does.
My one big guess is that I plugged my switch into a 3rd party USB-C hub (The ones most Mac users would need) when it was new before all the articles about how it's bad for you switch were released.
I'm guessing that the bad hub somehow triggered a fuse.
Either I get my switch repaired or I wait for non-rcm/usb port exploit.
Well, that's what I WOULD say if I hadn't just bought a used switch, tablet only, on ebay yesterday.