For mental blocks in general I will say that getting spotted over and over will generally not help you come out of the block, you need to do whatever skill you can do by yourself on whatever surface you can do it. You need to start with the basics, go through a warm up of handstands and cartwheels and the continue on till you get to the skill that you can't do alone and work on that skill as if you have never done it before. There is no use trying to worry about your full if you won't do a BHS by yourself. Also you have to take pride in whatever improvements you make, if you wouldn't do a back bend at the beginning of class but you will at the end then you made an improvement, it doesn't matter if you used to throw a double, if you finished class doing a skill or drill that you wouldn't do at the beginning then that class was productive. Most mental blocks can be avoided by slower progressions with a strong foundation of drills, and NOT USING SPOTS
For fulls specifically you need to do great layouts on a tumble trak (preferably into a pit or crash mat) with nice high sets and hollow body positions. During the layout you need to start spotting for the floor, if your eyes aren't open it's VERY hard to land a twisting skill. Once you are able to spot the floor every time before you land your layout then you need to start looking in the direction you twist right after you see the floor. So if you twist left you do round off bhs, high set, drive your toes, hollow layout, see the floor, look to the left, if you are nice and hollow this might make your body turn a bit but it might not. Do this over and over and over till you feel really comfortable and are ready to pull your shoulder and hip a small amount and land a quarter turn. These things take time and you can't rush, if you're not ready to twist alone you're not ready to twist at all, if you're not landing on your feet then you need to back up and do whatever skill you can land