Ylod is there after fix but not if I detach wi-fi board?

I dissasembled, reflowed and re-applied thermal paste on my ps3 because I encountered YLoD. While I was assembling ps3 i forget to attach wi-fi ribbon to wi-fi board and ps3 worked normally but controller obviously wouldn't connect. When attached ribbon back in place i got YLoD again. What can be the cause for that?