Over the past few days, we have extensively talked about the Galaxy Note 7 -- and its faulty battery. Amid announcements of a global recall, Samsung noted that it is rolling out a firmware update to let users know if their device is affected by the faulty battery. If the battery icon on the device turns green, it means the device is safe to use. The problem is that according to Google's Android Compatibility Definition Document, a set of guidelines that Google imposes on every OEM that opts for Google Mobile Services-enabled Android aren't supposed to tinker with things like battery icon. ArsTechnica reports:In the CDD, Google also defines some of the interface design -- usually the parts apps need to interact with, like the System UI and shared theme assets. This includes mandating the color of the status bar icons, which seems to throw a wrench in Samsung's publicized plans. The section titled "3.8.6. Themes" reads: "Android device implementations MUST use white for system status icons (such as signal strength and battery level) and notifications issued by the system, unless the icon is indicating a problematic status or an app requests a light status bar using the SYSTEM_UI_FLAG_LIGHT_STATUS_BAR flag." Google spells it out pretty clearly: status bar icons have to be white. They aren't allowed to be green, which is the color Samsung plans to use in a future update.