100 Doors Underground Stage 7 Walkthrough is shown below with screenshots. The answer for this level is explained in detail in the text. Look at the screenshots for more help. If you only want to look at part of the guide and not cheat, just look at part of the solution. This will help you go to the next level.
1. Pick up the chisel in the plant on the right and the hammer on the fireplace. Place the chisel inside the fireplace.
2. Shake your phone/device until there's a hole and you can see the key. Take the key and use it on the door.