Self-bondage Challenge
OK, we have now proven that with the key on the floor behind you, you can free yourself even with your hands crossed behind your back and cuffed. If you have any doubts about your ability to do so, find a way to address your concern before continuing.
Now, with the key on the floor behind you, cross your hands behind your back and lock them both into the handcuffs.
Before you unlock yourself, I have three tasks for you. First, you need to be mobile. Either stand up, or shift yourself along the floor, I don't care which. But you need to be able to move about 4 meters (about 12-feet, for you non-metric types) away from where you are now, and then come back. If you cannot do this, then unlock yourself and make whatever adjustments are necessary, then repeat the lock-one-hand test to make sure that you can still unlock yourself, then lock your hands back in and try again. When you do the pain challenge for real, your key will be about four meters away, so you absolutely need the ability to move that far while restrained. Do not continue with this challenge until you can do so.
Second, while you are back at your computer, do everything in your power to escape without using the key. You can use any object within four meters, you can try to break the belt or the rope. You can try anything other than using the key. If you are able to escape, then you must fix your binding so that this escape will not work again. This may mean removing the object you used to more than 4 meters away. It may mean replacing the belt or rope you broke with a more durable belt or rope. If you have to change anything about how you are restrained, then repeat the lock-one-hand test before locking both hands up, then repeat the move 4 meters test, then try to escape again. You should only continue when there is no possibility of escape without moving four meters away or using the key.
Finally, while still restrained, press continue. If you cannot do so, then use the key to free yourself, fix the problem so that you can operate your mouse while handcuffed like this, then repeat the earlier safety checks as necessary, cuff yourself back up, and press "Continue".