Even if the spindle cannot be gripped by any means, the hex key method described in the previous step will usually work on both corded and cordless models.

Many cordless drills have an automatic spindle lock.

On mains powered drills, inertia of motor and gears usually offers sufficient resistance to free the chuck from the spindle.

If you're relying solely on inertia, you need a sudden jolt to loosen the chuck. Press down hard on the drill to keep it from moving and hit the hex key with a particularly sharp blow.

This will take a steel hammer - much as you may hate to mistreat your beloved hex wrench like that - as a plastic or wooden hammer would cushion the impact.