Got to the bottom of these and thought I’d share the knowledge.
One phone had a short on "C3 image processor / Samsung S2MPB02 PMIC" (VDD_COMP_CORE_0P8) I didn’t think the caps looked bad so I removed the IC itself and the short went away, the device booted again with full image only camera not working, data is all fine though which was the main concern.
The other phone however was not solvable. a full short to ground was found on VDD_0P8_CP by comparing board values. Two caps and one filter removed for this small line and short still present. Lower bigger PMIC removed and short still present. The only place left is the CPU, I had to call this one a day because replacing the CPU is out of my depths (even then it may be unique with the hardware encryption.