Be careful, following these instructions can leave you with a board in a difficult to recover state!

1. Put this in code.py:

print("hello world")
while True:
  pass

2. reset the board
3. connect via usb-cdc to repl
4. hit "A" then "ctrl-c"

Normally, you'd expect the ctrl-c to interrupt. However, it doesn't. If "ctrl-c" is the FIRST thing typed through usb-cdc, then it probably works. But typing anything else first leaves it non-working. My Linux terminal program announces that it can't send characters through the serial link anymore.

@ladyada and I both ran into a form of this, me on the mimxrt1010-evk and her on the metro m7 prototype.

We're assuming it's mimxrt10xx only but didn't test other micros.