Answer to "What should I do when recieving an "Invalid Sim Card" message?"Also make sure your device is up to date on all the software updates and updates for your device. I have an HTC that kept freezing then wouldn't even get past the opening screen because I neglected to update it. It was a pain in the butt to fix because the guy had to change the whole motherboard inside the phone. Eventually I got it back in working condition but I now make sure that my device is completely updated for the device itself and all software.