Highroyds

Hi, I’ve been trying to fix an Xbox which used to work perfectly. I tried to do the wii to hdmi mod and screwed it up, so put the old av port back on and confirmed all the pins going to where they should go, but it started fragging. I compared it with a working Xbox and found one line across the motherboard giving a strange diode reading of -1.1 or -1.0 when it should be 0.497 (red probe on ground). I’m attaching 2 photos showing a red line where this strange reading is. Any advice would be grateful.