./scripts/flash-sdcard.sh /dev/ttyACM0 artillery-ruby
Flashing /home/pi/klipper/out/klipper.bin to /dev/ttyACM0
Checking FatFS CFFI Build...
Connecting to MCU............................................................................................

SD Card Flash Error: Unable to connect to MCU
Traceback (most recent call last):
  File "/home/pi/klipper/scripts/spi_flash/spi_flash.py", line 1202, in main
    spiflash.run()
  File "/home/pi/klipper/scripts/spi_flash/spi_flash.py", line 1151, in run
    self.run_reactor_task(self.run_reset)
  File "/home/pi/klipper/scripts/spi_flash/spi_flash.py", line 1138, in run_reactor_task
    k_reactor.run()
  File "/home/pi/klipper/klippy/reactor.py", line 269, in run
    g_next.switch()
  File "/home/pi/klipper/klippy/reactor.py", line 310, in _dispatch_loop
    timeout = self._check_timers(eventtime, busy)
  File "/home/pi/klipper/klippy/reactor.py", line 156, in _check_timers
    t.waketime = waketime = t.callback(eventtime)
  File "/home/pi/klipper/klippy/reactor.py", line 48, in invoke
    res = self.callback(eventtime)
  File "/home/pi/klipper/scripts/spi_flash/spi_flash.py", line 1097, in run_reset
    self.mcu_conn.connect()
  File "/home/pi/klipper/scripts/spi_flash/spi_flash.py", line 820, in connect
    raise SPIFlashError("Unable to connect to MCU")
SPIFlashError: Unable to connect to MCU