This page will show one way how to get root access via a serial cable. (See here for details about the cable and the connection.)

To get access to a linux console with root rights, there are several methods. I used the following method:

1. Power off printer
2. Write following lines in a flashforge_init.sh script:

   (cat <<- _EOF_
   #!/bin/sh
   set -x
    
   WORK_DIR=`dirname $0`
    
   #Test the machine's architecture and quit immediately if there's an error.
   CHECK_ARCH=`uname -m`
   if [ "${CHECK_ARCH}" != "armv7l" ];then
       echo "Machine architecture error."
       echo ${CHECK_ARCH}
       exit 1
   fi
    
   # Ask user to change root password
   $WORK_DIR/play
   cp /etc/shadow /etc/shadow_old
   cat /etc/shadow
   passwd
   sync
   $WORK_DIR/play
    
   exit 0
   ) > ~/flashforge_init.sh

3. Format a usb stick to FAT32, download a Flashforge update file and extract all files to the usb stick.
4. Overwrite flashforge_init.sh with the one from above.
5. Connect printer via serial connection at the mainboard. Connect using 115200 8n1. E.g.:

       minicom -b 115200 -D /dev/ttyUSB0 -C serial_port_115200.pw_change.txt

6. Insert usb stick in 3d printer and power-on
7. Verify kernel log messages output in minicom
8. Enter a new password when asked for.
9. Wait until the music is finished. Power off printer. Remove usb stick and power on. try to login via serial. Connect using:
   user: root
   password: The password which was just entered.