Arduino Nano Every - macOS Mojave - avrdude: jtagmkII_getsync(): sign-on command

Development Tools IDE 1.x
1

I have tried both these links. Unfortunately none of these two helped.

https://forum.arduino.cc/index.php?topic=701815.0
https://forum.arduino.cc/index.php?topic=631163.0

I have:
Arduino Nano Every (ATMEGA4809) [I bought from official store: https://store.arduino.cc/usa/nano-every]
MacBook Pro: macOS Mojave (10.14.6)
Arduino megaAVR Board version 1.8.6 installed

If go to my Tools
Board: Arduino Nano Every
Registers emulation: "None (ATMEGA4809)"

I see that the Serial Port is NOT available.
The available ports I see:
/dev/cu.Bluetooth-Incoming-Port
/dev/cu.D015-SPP
/dev/cu.D015-SPP-2

I tried with all these 3 ports, but no luck.

If I do:
$ avrdude
I get this:
avrdude version 6.3, URL: http://savannah.nongnu.org/projects/avrdude/

And if I do:
$ locate avrdude
I get this:
/usr/local/Homebrew/Library/Taps/homebrew/homebrew-core/Formula/avrdude.rb
/usr/local/texlive/2019/texmf-dist/doc/latex/shdoc/avrdude-log.save

Following the question in "topic=701815.0", I tried with different USB cables, but no luck.

If I try the "Blink" example in "01.Basics:Blink"
I am getting this error:

avrdude: jtagmkII_getsync(): sign-on command: status -1

Also I tried from the "Arduino Web Editor"

I can't open my Serial Monitor. It says "Serial port unavailable"

And if I try to upload the same Blink example, it says,
"Error uploading, check if the selected board is currently available".

However, my Arduino do blinks by default when I connect it with any USB.

Thanks in advance for any suggestions!

2

When I tried again, with another USB cable, I now get a new error.
Also, it has found a new port:
/dev/cu.usbmodem14401 (Arduino Nano Every)

Thus, when I try from this new port, I get the following error:
avrdude: jtagmkII_initialize(): Cannot locate "flash" and "boot" memories in description

However, I just learnt that, this is a warning message and can be ignored!
https://forum.arduino.cc/index.php?topic=632558.0

I just now, changed the default frequency of the LED High and Low, and I see that it is perfectly working!!!