Difficulty uploading to a Motieno. "Programmer not responding"

Tried using both a machine running OS X 10.11.6 and one using some version of Windows 10 (not my machine so I’m not as certain about those configurations.

The board I’m attempting to upload to is a Moteino Mega from LowPowerLab.

I have never been able to upload to this board. The examples compile just fine but when it’s time to upload they’ve never really got past the point described in the error below.

This is the (verbose) upload message I get:

         avrdude: Version 6.3, compiled on Dec 16 2016 at 13:32:25
         Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
         Copyright (c) 2007-2014 Joerg Wunsch

         System wide configuration file is "/Users/<omitted>/Library/Arduino15/packages/Moteino/hardware/avr/1.2.0/avrdude.conf"
User configuration file is "/Users/<omitted>/.avrduderc"
         User configuration file does not exist or is not a regular file, skipping

         Using Port                    : /dev/cu.usbserial-DN01QBAQ
         Using Programmer              : arduino
         Overriding Baud Rate          : 115200
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.

Problem uploading to board.  See http://www.arduino.cc/en/Guide/Troubleshooting#upload for suggestions.

I have looked around for details on this error. Most of the suggestions seem to involve drivers and/or resetting it. As near as I can tell I have the appropriate drivers (the USB serial port shows up when I connect the board and disappears when I disconnect it). I’ve tried resetting it at various points during the upload with no effect on the message I receive.

I have installed via the board manager the Motion Mega board and tried uploading both with that board and with the default ardurino board that the chip selected naturally when I first attached it.

The light is blinking which is supposed to indicate that there is a bootloader working. I have not tried messing with either the bootloader or the programmer as I’m not sure what that would do (I am new to this).

If anyone could help me discover what the issue is, I’d appreciate it.