- The battery (connected to
BAT+) typically goes to a Li-ion battery management IC, then to a 3.3V regulator. - The 5V pin (
VUSB) is now disconnected from any valid power rail and is floating. - The random voltage (0.1V to 1.8V) you’re seeing is due to leakage currents or residual capacitance — it’s not usable power and not expected to be stable.