While not new to Arduino, I am still a beginner. Last month I used one on 2 Halloween Props. I have 2 arduino Uno's both R3's, Made in Italy legit ARduino's probably 5 years old. I am a middle school teacher, so middle schooler have used these in the past. We don't currently teach Arduino in my classes.
Uno #1: No port.
So I hook up the unit and the port is grayed out. So the computer does not recognize the port.
Uno #2: Computer sees the port just fine. I upload a sketch and Led #13, tx and rx blink a few times. Then the IDE says:
avrdude: verification error, first mismatch at byte 0x0000
0x0c != 0x62
avrdude: verification error; content mismatch
I have read this has to do with a bootleg or bootfile, I don't understand this.
Things I have done to both Uno's:
Changed USB cable
Used IDE 1.8.5
Uninstalled and reinstalled IDE 1.8.5
Uninstalled and installed IDE 1.0.5
Tried the web creator
Tried the web creator on a Mac (I have a PC)
Switched the computer chips between the Unos.
Tried all USB ports on Mac and PC
Read forums and internet for 3 hours!
Advice please. Thank you so much.