This paper describes a thorough investigation to identify the root cause of an LCD panel burn-in failure induced by an LCD source driver, which is observed in a large-scale LCD factory producing more than one million LCD panels per month. The investigation demonstrates the effectiveness of the circuit simulation to precisely locate the defective spot which is caused by a metal slice originated from outer rings of an LCD COG (chip-on-glass) source driver. With the aid of emission microscope (EMMI), Energy Dispersive Analysis X-Ray (EDAX), and Chip Probing (CP) tester, the root cause of the failure is well explained. The formation mechanism of metal slice from the outer rings is thoroughly studied. A solution to completely eliminate the source of metal slices from the outer rings during wafer processing is also proposed.