Hm-m-m-m... well... since I'm an old man it's been many years since I was in school (thankfully.) One thing in your post that jumps out at me is the fact you're awake & on-line at 2 a.m. I don't know if that's typical for you of course. But, if so, one thing you might consider is that everything is much more difficult when you're not rested. I know myself when I don't get enough sleep it's harder to focus, harder to understand something I might be reading (such as posts here on PC), & much easier to become irritated at even the smallest provocations.

As I recall you had mentioned, in your introductory post, social anxiety is something you struggle with. Perhaps your reluctance to seek help also has something to do with that? Being stubborn & wanting to do everything yourself isn't necessarily a bad thing to my way of thinking as long as it doesn't result in you not completing your school assignments to the best of your ability. However, if this "locking" is something that is affecting your performance then perhaps it is something you ought to address. I wonder if there might be a teacher, or school counselor, you could "brainstorm" with regarding how to get past your inhibition.

I don't know as there are any particular techniques I could suggest for overcoming something such as this. One way to look at it, perhaps, might be to see it simply as a bad habit you need to change. Here are links to 3 articles, from PC's archives, that discuss effective ways to change a bad habit. The third article includes a video on the subject you can watch:

Science Says This Is How to Break Any Bad Habit

The Golden Rule of Habit Change

3 Steps to Change a Habit | Channel N

And while we're on the subject... here are links to 2 articles, also from PC's archives, that discuss good study habits:

10 Highly Effective Study Habits

2 Important Strategies for Effective Studying