The owner of this board tried to install an internal sd2iec adaptor on the internal IEC header.
IEC not working anymore..
Let have a closer look..
First I removed the solder and wires parts from CN4B, then I removed the silkscreen from the board to see the damage. Some vias are messed up, and 1 trace was broken.
Placed a pinheader on CN4B and fixed the broken trace with a jumpwire. after that, I connected my own external SD2IEC adaptor and tried to load Giana Sisters.. And it worked!
ALso checked all the traces from CN4B, and everything looked good.