Arduino trouble

Hi
Im really struggling to understand whats going wrong
I was using elegoo clone with smc3 sketch all was fine till i had a short and pin a0 was just producing noise and not receiving any signal from pot
Pin a1 worked with both pots pin a0 just random noise
So i purchased a genuine arduino
The clone showed green and orange lights and showed up as arduino on comm port 3 it also had the square USB port and long chip

The genuine is showing 2 red lights 1 flashing and shows up as serial usb on com port 4 and has usb-c port with the small square chip

I try to write the smc3 script and it says com port 4 access denied
I can copy the error and paste when i open up my pc
Please somebody help me understand im stuck after doing so well
Kind regards
Matt

What I did NB is changed on uno R3

const int FeedbackPin1 = A0; // Motor 1 feedback pin

to


const int FeedbackPin1 = A3; // Motor 1 feedback pin

i think theres a prob with the uno R4 either the board or the usb-c

the pin change seems to have done the trick

thanx for replying