When trying to upload code, a bunch of errors appeared in the console, I remember seeing the word butterfly. Now, only the blue LED is on, and the board isn't recognized by two different computers I've tried. If I press the reset button twice the green LED turns on getting dim and bright over and over for about 5 seconds. During this period I can detect the arduino on my computer, but in a few seconds the light shuts off and it can't be detected. The same thing happens if I short the two pins on the ICSP header. I've been powering it via a USB port from both computers.
I was able to fix my problem. I double clicked on reset and tried to upload an empty sketch to my arduino in the few seconds it stayed on. It worked successfully and is now permanently detected by my computer. If anyone else has this problem, follow these steps:
Attempt to upload an empty sketch when the arduino is not detected, so it compiles faster the second time.
Double click the reset button or short ICSP to get it to boot, and then immediately hit upload.
Hopefully the upload completes before the arduino crashes again, and if it does it should work now.
I had two arduino working fine, then suddenly none of them are being detected on my laptop until I press the reset button. which makes it discoverable for a second or two only, then its get unplugged again. I can't upload an empty sketch because there's isn't enough time for that.
Are you using a Arduino Micro as OP did? If not, which board do you use?
Anyway, the following might work
Start an upload; when the IDE reports the memory usage, press and release the reset button.