Well thats not good.

Just as I figured out what was going on with my trace and was happy things were finally working, I dropped a scope ground clip on the board while it was live and now the FPGA is getting hot and 1V8 is clamping at about 1.0V.

It's only an xc7s25 so not a HUGE loss, i'd be a lot more cranky if it was an ultrascale or something. But I'm still not looking forward to having to do BGA rework to repair the board.

FPGA removed and BGA site cleaned, and all rails came up OK.

Best guess is I dropped the ground clip between the 1V8 rail and something else and blew the VCCAUX rail of the FPGA.

At least nothing *else* was on that rail, so the rest of the board should be OK. And I have a spare, and it was only a $40 part.

Grrr, I don't think I'm saving this board. Put a new FPGA on but couldn't get it soldered properly with hot air, and it can't go back in the oven without damaging other components.

I guess I can try an oven cycle and then accept the risk of damage to the RJ45 and/or power jack and rework those if needed. Can't make the problem worse at this point.

Stuck it back in the oven and saw the new FPGA nicely self-center (which I wasn't getting with hot air, I was melting one part at a time and it'd instantly re-solidify after... even with bottom IR preheat).

No visible damage to the RJ45 or DC jack so this might actually have worked out.

Still too hot to test. DC inlet is visibly browned, light pipes on the RJ45 are definitely sagging.

PMOD connectors don't seem too happy either.

But those are all minor things I can tolerate the loss of, and rework easily with an iron if I need them.

And everything seems to be working! The board is alive and responsive over Ethernet, trace works, all of the MCUs and the FPGA are talking to me.

@azonenberg reminds me of the time I had a scope probe's ground (a spring contact) flick out and short the 1v0 rail. 25A sure made it glow. naturally my finger was resting on it.