Since these three defects are all on power IC TPS23753, so we check the defect IC in detail and compare with good one then found Pin 7,8 &9 related to power circuit were in abnormal impedance . So we judge the result was caused from overvoltage no matter from PoE switch or setup environment(lighting or equipment might not grounding well). If needed, we can check what kind of PoE was used from the environment for further testing.