Why does the key fob battery for Citroen Saxo keep going flat?

The key fob battery for a Citroen Saxo may keep going flat due to several reasons, including a faulty battery, which may not hold a charge effectively. Additionally, if the key fob is frequently used or has a malfunctioning circuit, it can drain the battery more quickly. Environmental factors like extreme temperatures can also affect battery performance. Lastly, any stuck buttons or internal damage could lead to continuous power drainage.