For what it's worth I had/am still having problems with my GI boards failing at an alarming rate; about 7 in the last 4-5 months.
I have late run standard WOZ built in late 2015. My personal experience with this issue after 3 years of dealing with this problem (on location) I found that I had a large number of poorly built data cables that were probably the main issue. If you look at the cables that were connecting the bad boards are they heat shrinked at both ends? (sometimes they are color coded red and green, other times they are both black) Personally the majority of my failed boards had unwrapped cables where one or more of the colored wires were frayed and touching each other and/or the outer shielding.

I just bought 6 new data cables from them the other day (you have to call them to order as the web store is being upgraded and they are not listed) they range from $4 to $9 each plus shipping.

BTW my latest problem looked exactly like yours, it was a failed #3 GI board and all the cables from #3 out (red) to Gi #6 were frayed and not heat shrinked.