The last level is very unintuitive and I'm not even sure that the way I did it is correct. I basically raised the giant block shot the magnet through the tiny gap to try to get it to land in the little pit where the block is to prevent it from hitting the button so I could jump across and get the key. The problem with this is that sometimes, the magnet hitbox is too large and doesn't go through the hole or doesn't get into the right spot because it requires a really precise angle.