This paper illustrated the beauty of AFP nanoprobing as the critical failure analysis tool in resolving the one-time programmable (OTP) non-volatile memory data retention failures through electrical simulation in wafer fabrication. Layout analysis, electrical simulation using Meilke’s method, UV erase methodology (to differentiate between mobile ion Meilke’s method contamination and charge trap centers) and a few other FA approaches were employed to determine the different root causes in the three OTP failure case detailed in this paper.. These include SiN trap center issue, poly stringers and abnormal layer at the initial CESL (Contact etch stop layer) nitride. This paper placed a strong emphasis on systematic problem solving approach, deep dive and use of right FA approach/tool that are essentially critical to FA analysts in wafer foundry since there is always minimal available data provided. It would serve as a good reference to wafer Fab that encountered such issue.