Signs of Broken Torsion
Torsion springs are the driving force behind your door. They balance the weight of the door and lift it. Springs are very DANGEROUS as they are under a lot of tension.
Here are some signs you may have a broken spring.
Visual Broken Spring
Door wont lift with motor or manually
Large "Bang" when closing door
It's VERY important to not attempt to lift the door if the springs have broken, they are very heavy.
Also, as you near the full opening height one cable can come loose causing the door to skew and potentially fall out of the horizontal tracks causing damage to both yourself or car.
Torsion springs are the driving force behind your garage door