Standard roll over cables should work. The wiring configuration from an RJ45 perspective is pins 1-8,2-7,3-6,4-5,5-4,6-3,7-2,8-1 this in effect shows a mirror image, although you will need to adapt for a DB9 console connection. After that putty and serial connections should provide you with the output to determine the cause of the fault. Standard trinal settings you'd use in any other 9.6k terminal connection. Good luck.