Checking if developer mode is enabled on the device is the first step to confirm if the user or a third-party has made unauthorized changes to the system settings or installed applications that require developer-level access. Enabling this mode is often necessary for rooting or jailbreaking a device, which can lead to security compromises. This step is a good first check because it is a quick action and can immediately give insight into whether the device has had modifications that could lead to the symptoms described. Reinstalling the OS or performing a factory reset are potential subsequent steps but should not be the first action taken, as they can lead to data loss and might not be necessary if the issue is simply that developer mode has been turned on without malicious intent. Checking for OS updates is important for device security but would not directly confirm whether the device has been compromised through the actions enabled by developer mode.