It was the same for me. The first time, just apply a little more pressure. It won't break. After that, it should be easier to open the treadmill.

It was the same for me, but don't worry. Just help it along with a little force, it won't break ;)

If you want to be on the safe side, you can loosen it a little bit with the supplied 6 Kant spanner. Loosen the whole thing on both sides at the beginning of the treadmill.