I don't know what is causing this to happen. I have zero interest in unlocking this phone, I don't even know how to do that. I was just watching a YouTube video when i got three notifications. One saying sim card is not readable, second one saying please contact sprint to unlock your device and the last one saying invalid sim card. I have no idea how to fix this or what could be causing it. I just want my phone to go back to normal. Does anyone know what is causing this and if so can you please help me.