Since your removing the boards, you should be able to remove the front panel to try to straighten it. You’ve got nothing to lose. First try placing it on the floor supported by 2x4’s on both sides, bow side up and step on the high spots. Use a straight edge to check frequently. Try bouncing on it a bit. If that doesn’t work, find something that is stiff like an I-beam, large angle iron, welding table top or a stout wooden board (2x8 - 2x10, etc.) to take the place of the floor and support it like you did on the floor but instead of standing on it, use large c-clamps. To straighten the dents in the top rail, find something metal (cylindrical or a pipe if you can find one that fits) that just fits inside the and as you pass it thru, it will get stuck where the dents are. Use a hammer to tap it back into shape using the cylindrical metal object as a dolly. You might have to drive it thru as your tapping to remove the dents.
If all else fails, you can always buy a new one. Good luck and have fun!
