What's going on here?
 

So I finally got around to pulling my 9920 and checking it out, and the shrink appeared to have been heated up pretty good. Upon pulling it off I found this spot underneath. At first i thought some glue had heated up and melted all over the cap, but now I'm not so sure. Did the cap leak from the backside, or did the FET melt away? Underneath it looks hollowed out a bit...still ran though. Just got hot quick.

Looks like maybe a cap burst or something...Not sure...That is probably why your controller runs hot with the 7XL :p.

Did you use the BEC? It's hard to tell, but it looks like the IC for the BEC regulator heated up and caused the glue to melt. It's hard to tell.

Either way, it does not look good!!!

True, but at least if it was from the BEC, you at least know that you shouldn't use it anymore since the load is too high. Although, now that I look carefully, I see a little more scorch marks near the top left edge of the picture. What is going on there?

Since the BEC is not on the same layer as the drive FETs, has anyone thought to add a heatsink there?

I didn't use built in BEC, but I was thinking that is what looks burnt, though. Maybe I cooked it a long time ago and it just slowly let go more and more. No doubt that's why it ran hot with the 7XL. :)