Fix init sequence in Raspberry Pi

If the init sequence gets broken and you can't get to a shell on a Raspberry Pi (I'm using 3 model B), you can boot into recovery mode this way.

• Hit shift when starting up.
• Hit "e" to edit config
• tab over to cmdline.txt
• add to the end of the line
  init=/bin/sh
• hit ok, then Esc to boot...... it will boot you in to a command line
  # mount -n -o remount,rw / (this will remount / so you can make changes)
• now you should be able to edit the init.d config.
• when you reboot again.... hold shift and remove the init=/bin/sh

Source: raspberrypi.stackexchange.com