Arduino Nano's won't load, blue LED on

Guys, I have some Nano's that I am trying to program and when I do, instead of a red light, then a blinking green light during loading, I get the red light plus a blue light, which just blinks constantly. Three of four are like that where they were working fine before, what have I done to them?

They are not connected to anything other than the USB cable, and the same happens on different PC's

Any ideas?



Does the upload fail? If so, please do this:

  • (In the Arduino IDE) File > Preferences
  • Uncheck the checkbox next to “Show verbose output during: compilation”
  • Check the checkbox next to "Show verbose output during: upload
  • Click “OK”
  • Sketch > Upload
  • After the upload fails, you’ll see a button on the right side of the orange bar “Copy error messages” (or the icon that looks like two pieces of paper at the top right corner of the black console window in the Arduino Web Editor). Click that button.
  • In a forum reply here, click on the reply field.
  • Click the </> button on the forum toolbar. This will add the forum’s code tags markup to your reply.
  • Press “Ctrl + V”. This will paste the upload output between the code tags.
  • Move the cursor outside of the code tags before you add any additional text to your reply.


Some of us are not 'Guys'!!!!!

English is not my native language. It's however my understanding that in the given context it is acceptable to use "guys" when addressing a group of people of mixed gender.

Please correct me if I'm wrong. If I'm wrong, what would be the correct way? "people"?