Causes For Fob To Go Out Of Synchronization

Depressing a fob button while disconnecting vehicle battery or power to Entry Module.
Pressing both fob buttons for five seconds or longer when out of range of vehicle or when power has been disconnected to Entry Module.
Pressing fob button more than 256 times when out of range of vehicle or when power has been disconnected to Entry Module.
Taking fob apart, followed by putting it back together and pressing fob buttons more than 10 times when out of range of vehicle or when power has been disconnected to Entry Module.