Chosen Solution
Cutting the line was meant figuratively (as a metaphor). If you look at the image below you will see hot the PP_CPU/GPU lines are configured:
You’ll note that the voltage is created by the PMIC, goes through and inductor and then is filtered/bypassed by a bunch of capacitors before heading off to the CPU/GPU. If there is a true short on that line (i.e. <1 Ohm), then it is either the PMIC, one or more capacitors or the CPU/GPU. So you start by removing capacitors to see if they are causing the short. When you have done that and the short is still present, then you know the short is either the PMIC or CPU. Removing the PMIC and or the CPU to test for shorts is quite difficult so instead you could “cut the line” by removing the inductors. Then you measure for shorts on each side of the inductor pads to see if the short is with the PMIC or CPU. Keep in mind that removing these inductors can be a destructive process so make sure you have replacements on hand before doing this. On some devices, like the iPhone 6, removing the PMIC is much easier but on the 6S, the PMIC is glued in with underfill and directly opposite the CPU so removing it can be very risky.
