Nano clone not working over USB, no data, no power, but can power via Vin (CH340 chip? schottky diode?)
Either you have a cable problem or that board is just not working well.

What you call the CH340 chip - when they go bad you get power but NO communications, in my experience.  You can test voltages at the various points like 5V, 3.3V, etc., to see if it getting power.  If it is and you're still not communicating, then if it were me it would go on the shelf for the kids to see.  

It no longer can trusted.

Rather than troubleshooting the board it would be worth getting another to compare with.

And if you have more than one cable on hand, try them and see if there are any differences.

But my prediction is that a new board will work and this one will continue to not work.