L- is a "Link Error" 

  • Security thumb drive is not connecting because the computer is not booting up
  • Gray ribbon cable is in the wrong position or backward
  • Fault in the computer
  • Ram is dirty
  • Connection issue on I/O Board
  • Fault led control board causing a drop in voltage across the communication channel.
  • Please look over the attached files if the issue is the led control boards.