Does the manufacturer of the laptop have the means to determine if the drive failed from impact damage.
The dent in the case should give them a clue. <g> It is also possible that the mfr. has installed an internal shock/impact sensor
There are other tell-tale signs of large shocks as well. Many if not most modern laptops include accelerometers on the motherboard, which are used to unload the HDD heads when a fall is detected. These can be damaged by excessive shock. For example in the ThinkPad T520 Service manual motherboard replacement section it states:
Important notices for handling the system board:
When handling the system board, bear the following in mind.
• The system board has an accelerometer, which can be broken by applying several thousands of G-forces.
Note: Dropping a system board from a height of as little as 6 inches so that it falls flat on a hard bench can subject the accelerometer to as much as 6,000 G's of shock.
• Be careful not to drop the system board on a bench top that has a hard surface, such as metal, wood, or composite.
Most mfr. warranties will require that the entire system be sent in, which in this case would make the physical damage obvious. At that point they may decline to replace the HDD under warranty. Let me know how the story ends... Scott.