2007 Toyota 4Runner Electronic 4x4

My wifes 4runner when we turned the dial to 4x4 high the lights on the dash just blinked. We took it to the dealer and they said that the motor that locks in the front differential? for 4x4 high was out. Also the rear motor that locks it in 4x4 low was out. We have never even used the 4x4 low. She babies this truck. Last year there was rattle in the dash which they dismantled and replaced parts in. Could they have shorted out the motors or hooked something up wrong then and fried those electric motors? Also the sunroof has been replaced because it was rattling. Could that have caused an electrical short for the motors.

What's the chances of both motors going out at the same time?

Thanks,
Craig