Is It Truly Possible?

I wrote to you here a month ago that I would like to submit a screenplay to a huge competition that has its deadline for April 30th. I’ve never written a screenplay before and this competition is only once a year and I wanted to push myself to make it to this year’s deadline.
What happened over March is that I kept changing the story I want to write about and here I am on April 3rd with blank screen in front of me.

Yesterday I heard my brain telling me: Clearly now it will be impossible for you to write a screenplay in one month, even less than one month. Just give up the goal and do it next year.
And for a moment it felt comforting and I could breathe again, but then I realized that I was tricked by my freaked out brain who sought a relief from the Herculean task and I decided I can’t afford NOT to submit this year.

Taking about 100 pages long screenplay, my brain still tries to calculate simple math and tells me it is undoable. That even if I wrote every single day with no off days, how could I possibly write something that is readable and coherent in such a short amount of time.

What do you suggest I do to make it possible against all odds?