Once you're set up, you start pulling fuses to id the circuit (unless you have experience with particular makes/models and want to start there). It may be your wiper motor can't park anymore but it keeps trying. Or the damage makes the object detection in the rear bumper scan all the time, even when shut off.
How do batteries get damaged?
Batteries can become damaged from overcharging, physical damage, or simply age. When a battery is overcharged, it causes the chemical reaction inside the battery to happen too quickly, which damages the cells and shortens the battery's lifespan.
Sometimes, vehicle battery damage may result in an inconsistent power supply to start the vehicle. For instance, when the power supply is too high, an increase in resistance blows the ignition fuse. Also, when the power supply and wire are small in size, it develops more heat which the ignition fuse cannot withstand, thus blowing out the fuse.
According to media reports, there is no way to repair or assess a slightly damaged battery pack of an electric vehicle after an accident. This has forced insurance companies to write off cars even with few miles.
So when you roll the batteries around or take them out and put them back in, you're actually just removing part of that oxide layer, allowing the electrons to move again. Others theorize that moving the batteries around works because you're moving the chemicals around, introducing them to the last bits of electrolyte left in the battery.
When your car has been involved in any type of rear-end collision, even when the damage seems superficial, don't take chances with hidden problems that can jeopardize your safety later. Instead, bring it to a dependable auto body shop to have the damage inspected, inside and out.
In the event of a subsequent, high-impact collision, a previously-weakened frame could give way and not protect you as it was designed to. Whenever your car has sustained any type of damage from a rear-end impact, get the frame inspected promptly at an auto body shop in your area.