How to unbend the bottom of a garage door?

The bottom panel of a garage door bends when a car bumper, lawnmower, or pet bumps into it, and you can usually fix it without replacing the whole door. Start by disconnecting the opener and lifting the door manually so the panel is at chest height with no tension on it. Loosen but do not remove the hinges connecting the bottom panel to the panel above. Place a wood block over the bent area on the inside of the door, then tap the block with a rubber mallet to gradually push the metal back toward flat. For deeper dents, install a horizontal U-shaped reinforcement strut across the inside of the panel. Re-tighten the hinges, reattach the opener, and test balance.