Really difficult to loosen up because there's additional lines in the way of the torx (m40) bolt to adjust with from the bottom. I looked at two videos, one guy struggled with it, the other notched the bolt from the top to adjust it.
I took a simpler approach. The bolt is M8x1.5 threaded. I picked up two nuts from ACE, and threaded both onto the bolt and locked them up. I then just used a ratchet and socket from the top to drive it down loosening the belt, and a box wrench to walk it back up to tighten it.
Doing this you don't need to remove the under tray, and you don't need to cut your hands up on a weird hit for the socket. You hold the bottom nut with the box wrench, and loosen the top one and remove both when finished. Everything remains undamaged and serviced.