Noun clause in negative form

My question is about noun clause in the negative form.

So here is the sentence:

But what you can do is don’t give up.

Can I use the negative form (don’t) in the second part of the sentence? And if so, is it grammatically correct? Should I use "not" instead of "don’t"?

Here is the context so you could understand the meaning of the sentence better:

Jack, you can’t just let it go. But what you can do is don’t give up. I believe in you. You have to try to do it for one more time.