Finding shorts can be a pain. Before assuming it is CPU related, you have to rule out everything else. Now you could have two separate shorts/issues, especially on a water damaged device but there could also be a common failure point.
Start with PP1V1 as it is a bit easier to follow. It is generated by the PMIC, feeds into the CPU and Acorn. PP1V1 is always used as a supply for downstream PMIC LDO outputs so you’ll want to check all of the PMIC LDO’s that are lower than 1.1V as they may be pulling down the line indirectly.
PP1V8 is used more widely but you essentially have to do the same thing. Find the starting point (PMIC) and follow it through. It could be a cap or it could be an IC so you have to rule things out one at a time. Use the visible water damage as clues but sometimes there are no visibly obvious clues to the failure. Freeze spray or Thermal camera may help if the short is giving off heat.