Can't upload Blink on 19 Student Kits: Uno R3 Mac OS10 +Mac OS11

[alepore]

Can't upload Blink on any of the (19!) Student Kits just purchased
All 19 kits have the same generic AVR dude error
*MacBook Pro with Mac OS 10.15.7
*IDE 1.8.6 installed
Second Configuration tested:
*M1 Macs with Mac OS 13.2.1
*IDE 2.2.2
In both cases:

-IDE Sees the Board
-serial connection is listed as /dev/cu.usbmodem
-uploads of examples from the library including BLINK result in
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x00

Have been using various ardunio for over 10 years- never had an issue.
Have googled this and other Aavrdude errors and searched this forum and can tell you:
-Nothing in any ports
-no shields
-USB plug in all the way (all 19!)
-swapped out a few USBs (in case all 19 were duds)
-Unplugged and re-plugged
-hit reset
-didn't buy a clone from alibaba
-did buy 19 of these from the store on arduino.cc
-tried uninstalling AVR 1.8.6 and installing AVR 1.8.8 instead, then back to 1.8.6 (because why not?)

Before I devour a pint of ice cream in sadness at my school's lost $$$, is there anyone who has a suggestion not covered here, including how to request a refund, and what is safe to purchase from Arduino.cc instead? Still prefer it to Rasperry Pi and willing to give it another shot...

Thank you in advance,

[gilshultz]

I know nothing about a MAC but as I understand it is somewhat like linux. In linux there is a dialout you have to join before the IDE works. I vaguely remember reading something about a similar thing on the MAC on this forum a while back. You could always load Linux mint cinnamon on the MAC, it works great for me with the IDEs.

[westfw]

@alepore

-serial connection is listed as /dev/cu.usbmodem

Are you sure? My Arduino Uno shows up as cu.usbserialNNNN where NNNN is some random-looking digits. That might be because I'm running an older MacOS, or because I have more than one USB Serial device plugged it, but...

[xfpd]

Verify your cable is a data cable (not justt a power cable) and try one (or all) of the Arduinos through a good USB cable on another computer... listen for the "inserted" tone or look in dmesg or Windows device manager. It is unlikely all your boards died at once.