Well, I think I've got another case of blown FB24 and FB23. Modded 10 pods last night and one refused to hash although it was recognized by cpuminer. Opened it up and here is what I saw
I also noticed some bubbling on the centre chip and brown residue on the thermal pad.
I'm guessing the chip is gone, what are the odds the rest will work if I replace the beads? Anything I can check to confirm? Should I avoid using that barrel plug? It was working fine before the mod. I've got a multimeter and am not afraid to use it. Thanks in advance!
I think that your heat sink was not seated properly on the center chip and that is why it fried after you over-volted it. You can clearly see that there are no indents where the chips are supposed to contact with the top sink plate via the pad.
The center chip over heated (as it would be hotter when overclocked) shorted out and the 2 FB's released their magic black smoke.
That's all that happened. No big mystery.
Try re-seating the top half heat sink so it touches the chips like it's supposed to. Otherwise it will just act like a air flow shield and keep the chips from being cooled at all.
Of course, replace the bad chips first
Good luck!