A common mistake that happens when using optical transceivers is that users tend to accidentally burn them out by overpowering the input side of the module. In other words, the module gets damaged from the overabundance of incoming light signals. The use of long-haul transmission optical module in short-haul transmission will lead to excessive receiving optical power and burnout of optical module. The primary causes of optical module failure are performance degradation due to ESD damage, and optical path discontinuity caused by optical. This guide provides a comprehensive overview of common optical transceiver failure modes, including actionable troubleshooting strategies and advanced testing recommendations.