To people who uses CURA (> v3) for 3D printing and uses the same machine for programming Nano, I found out if you have Cura open and hook up your Nano, the Nano keeps restarting frequently (eventually it stops, but really annoying). Solution is to turn off Cura. Im using a Mac so dont know if this happens on Windows PC.
thought I'd share this little quark. Have a great day!