Continuing down the list of rails: 1V8 measures 1.7903V.
3V3 measures 3.29110V.
FPGA and (I think) main MCU are now responsive over JTAG.
1V2 only comes up to around 500 mV so something is shorted there, will investigate later. Pretty sure that rail is only used for the gigabit Ethernet PHY so it should be an easy fix once I find the short. Assuming it's not under the DC-DC itself which is frighteningly possible considering the state of the 1V8 PGOOD.