The tower is located directly behind the village the snails spawn in. I recommend using the well or other nearby objects to make the trip quicker. This is because jumping off walls makes your snail go faster, regardless of nearby snails. press "5" for scroll jump to get past the big bolder blocking the tower if it's in the way.

The newest update of the game allows the keys "F5" and "F8" to be used for saving checkpoints (F5) and getting to those checkpoints (F8). With the speed boost from step 1, save a checkpoint above the Tesla Tower, it's very important to save above the tower and not in it because going inside without a previous snail going in will kill you. If you do not have a speed boost then set a checkpoint right before you go in. When you respawn, get to that checkpoint with "F8" and now the shield won't kill you for another two minutes, a countdown appears on the screen surrounding the hat. When the countdown is nearing 0, jump up above the shield and set another checkpoint. repeat the process of going back to the new checkpoint and now you can get the hat/achievement.

It might take 2 or 3 checkpoints to get to the hat, but when you get close enough without the countdown turning the shield back on, you can grab the hat and the achievement should appear if you don't have it already.