That's tough; sorry to hear it. But every last square inch of vital leaf will assist in the plant's recovery.
I'm guessing this plant is from seed and not a clone, and in soil. If it were a clone or you have clones going, I'd say "do over". But there's also a lot of fun ime in scoring a cliffhanger save. My experience with milder nute burn is that it strikes like lightning but ends very quickly too ... so if your worry is about residual salts, I wouldn't worry. You flushed, right? If so, I would count any remaining green as still good. If a more seasoned grower disagrees, please chime in!
Out of curiosity, what medium (soil type/brand) and what nutes? Known strain or bagseed? Is this a first grow, and do you have other plants going under the same light (what light)? cn