I recently purchased 5 Arduino Nano clones and on my Windows PC they were all working fine. I then gave one to a friend and after installing the CH34OC driver on his Mac he was able to program a simple Morse code blink program that worked fine on the device. However, after uploading it the COM port was no longer showing and his Mac could no longer detect the device.
We verified that the problem was not with the Serial cable and not with the USB port and other the Arduino clones worked perfectly also. So it must be an issue with the device which when connected the RX and TX lights would stay on and the inbuilt LED would display the Morse code as was programmed. The device would then no longer even be registered by my computer as no noise was made when plugging it in and nothing showed up in device manager as if I simply pugged in a USB cable with nothing attached.
I then used my Arduino UNO to run the Arduino ISP program and then burn the bootloader onto my NANO. This was successful and the a new blink program was loaded and the TX light no longer shows when connected to my computer but it is still entirely undetected as if nothing was plugged in.
I have tries many things including but not limited to:
Holding the reset button when plugging it in
Reinstalling the driver as administrator
Switching out the cable
Changing the USB port
Using the old bootloader
Reinstalling the Arduino IDE
Restarting my computer.
Sadly nothing is working and I am out of ideas. Does anyone have any suggestions for a fix or know how I can diagnose the issue further. For example checking to see if the USB chip on the Arduino is operational or maybe the diode was faulty? Methods for testing these things would be greatly appreciated.