This voltage comes from U7500 controller, =PP5V_S0_REG voltage rails (L7510 inductor). Check LDO output (pin 7) , EN1 enable input (pin 14), VBST1 voltage (pin 17) and VIN (pin 6). Do you have any voltage to ground on =PPMCPCORE_S0_REG (L7560 inductor) at the same time? What is the resistance to ground on L7510?who generates the pp5v_s0