This article presents a comprehensive reverse engineering study applied to the Ecowitt WS90 weather station, a self-contained device designed to collect essential environmental data such as temperature, humidity, wind direction and speed, light and UV radiation levels, and precipitation. The main objective of this work is to gain a deep understanding of the internal workings of the weather station through meticulous analysis of its hardware and software components. The methods used are described in detail, including careful disassembly of the device, precise identification of key components, and scanning and disassembling the embedded firmware. Additionally, significant challenges encountered during the rigorous reverse engineering process are discussed and possible improvements or modifications to the original design based on the findings are proposed. The results obtained in this study provide an unprecedented insight into the internal workings of the Ecowitt WS90 weather station, contributing to a deeper understanding of environmental monitoring systems in general. The detailed findings presented in this article can be very useful for future developments and advances in the field of environmental monitoring, by facilitating the optimization of existing devices or the design of new innovative solutions. Furthermore, this work lays the foundation for future research and more specialized studies in the area of reverse engineering applied to environmental data acquisition systems.