Pro Micro board not responding to anything I just got a couple of Arduino Pro Micros for a custom keyboard build. Before testing them with the Arduino IDE, I tried to test them with qmk by shorting RST to GND to try and flash it. After a few seconds of holding RST, I got a single blink and nothing else, and qmk didn't seem to have detected the reset.
I've tried setting &quot;Board&quot; to &quot;Arduino Micro&quot; and &quot;Arduino Pro or Pro Mini&quot;. I'm on Arch Linux and no matter which USB port is plugged in, the IDE only shows /dev/ttyS0). I tried uploading the &quot;Blink&quot; example, as well as &quot;Burn Bootloader&quot;, but only got programmer is not responding like so:
avrdude: Version 6.3-20190619
         Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
         Copyright (c) 2007-2014 Joerg Wunsch

         Using Port                    : /dev/ttyS0
         Using Programmer              : arduino
         Overriding Baud Rate          : 19200
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 2 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 3 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 4 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 5 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 6 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 7 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 8 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 9 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0x00

avrdude done.  Thank you.
It turns out I had to use the port ttyACM0 (and not ttyS0) which wasn't found at the time. The port was there the next day and I have no idea why it wasn't there before.
Also, I thought I had to press and hold RST for a couple of seconds to reset the Pro Micro, but I actually have to press it twice in a row.
I've managed to flash the firmware for my keyboard by double-pressing RST.