Should I trim off the damaged leaves?

I hate to say this, but you should give up on this plant. Being an autoflower, it should have gone into flower a month ago. She's never going to produce any flowers for you and she's just taking up your time and your worry. Pop another seed and move forward. You switched nutes from week 1 to week 2 and this may have been a mistake. First of all, you gave nutes a little too early... autoflowers don't require nutes for the first couple of weeks and then, when you DO start them, you need to start them off about 1/4 strength to see if they're going to handle them and adjust. Keep the grow nutes going into pre-flower and at the same time, start your bloom nutes (about week 3-4) and start cutting the grow nutes back when they go into flower (week 4-5). If you're going to continue using Fox Farm, when you cut out Grow Big, start adding a small amount of Tiger Bloom... this will give the plant SOME nitrogen but not enough to lockout calcium. And as far as Big Bloom goes, I love that nute but 4T is a lot - max out at 3T and no more than 2tsp of Tiger Bloom. Things just got jumbled up on this particular grow and you did everything you could think of to save her - kudos for that! But now it's time to let her go, you'll have so much more knowledge for the NEXT grow that I know it will be great! Good luck!