This is a keystone model, but the same concepts should apply. Skip to 1:45 seconds in the vid to get to the slide out instructions for manual operation.
Basically what Grumpy said, but maybe the video will help you explain the process.
They need access to the motor that isn't working and the ability to hand crank it.
I would *not* have 2 dudes try to brute force the slide in unless it was an emergency. I'm assuming your friends have power and this is a failure, not an 'out of juice' issue...