The modules that contain microcontrollers can become locked up if they are subjected to a brown-out condition. In this case, the supply voltage drops to well below the minimum limit, but not all the way to ground. Some circuits can remain slightly powered while others shut down, resulting in register and memory corruption. This can cause unpredictable operation, including lock-up.
This can happen under several conditions. If there is a lot of capacitance on the supply line, the turn-on and turn-off times can be slow. If it takes more than 50-75ms for the supply line to reach Vcc min during turn on or to reach ground during turn-off, then there could be a problem.
If there are devices in the circuit that pull more current than the power supply can source, then the supply voltage will sag and can cause a brown-out condition. This can happen toward the end of a battery life or if there is a solder short, ESD damage or other damage to the board.
If the module locks up frequently, then it is recommended to monitor the supply line as the device is operated and make sure that it is sourcing the necessary voltage and current to the radio. There are other conditions that can cause a lock-up, but they are much more rare. If the voltage supply looks good, contact Linx Technical Support to check other possibilities.