PM_SLP_S* rails quick check
Most boards have DEBUG LED No-Stuff circuit on board.
You have all PM_SLP rails as well as PP3V3_S5 all together, on most MacBooks this circuit is placed on top of the board which means you can start the diagnostics without even removing it from case. Search for DBGLED to locate the area. Many test points here represent SLP signals. PP3v3_S5 can also be checked here. Since it is being enabled by SMC and generated from PPBUS, it also indicates functional PPBUS, PP3V42_G3HOT and SMC.