Motorguide xi5 issues

Hi, im new to the forum and was hoping to get some advice from any fellow anglers that own the Motorguide Xi5 with pinpoint gps.  I just bought a used model for "parts", the previous owner failed to install a breaker when installing on his boat, and it quit working. I opened the head and the white and red wires were melted, causing the red wire to actually break apart. After splicing the burnt wires, I ran resistance tests on the wires and they are still good. I even supplied power to the TM and verified voltage was being sent  from the control board, up through the curly wires and into the head. But im not getting any lights on the base, and no response from my controller. Think the control board fried? How could I troubleshoot it myself to rule out the cause of my problems? Thanks in advance!