Practice rolling from back to belly during the day. Like 5min/10times/day. From belly to back is easy so it is the back to belly we want to go.
Now to the rolled blankets, we put them UNDER the mattress so it forms like a cup, if you have them on the sides it is just a "buffer" if you get my point. You want it to be more like a bowl, that is why we put it under the mattress and also so they can't get tangled in anything.
The rest is perfect answers from MamaA, sometimes we also say, when you want to jingle, do house noice. When you want to enter the room, do the jingle. After that it is crisis if you get my drift? The major most difficult key to the cure is to learn how to listen and interpret the cry to "WHAT is the question" once you get this, you will always know what to do.
Like during the day you can hear if he is unhappy with something in his cry, if he wants something you have, you also hear if he falls it gets quiet and then the cry, your heart jumps because NOW you KNOW he got hurt, right?
Same thing with the cry during sleep, listen, listen, listen, interpret, THEN act accordingly.