Defective- 5v rail short circuit.

Hi, I have a 4Gb/64Gb board (S/N KBMP 160700402885/S70CR110-C45B) that has been intermittent in operation for several months. More recently it wouldnt boot into Windows 10. Today I reflashed the bios and a "read" check after programming indicated the updated bios file had downloaded correctly. After reconnecting keyboard, screen and power for about 20 seconds the power cable started to melt. I disconnected the 5v/5a power supply and a check with a multimeter measured about 0.6 ohm between the 5v pins and earth. The power supply was connected to the CN2 headers, not the mini USB. There are no signs of damage or overheating to the PCB. There is a small fan mounted on the heatsink.

Is it worth trying to repair and are there any suggestions as to possible faults.

Thanks in anticipation, Rod (VK5UV)