nothing you can do except just water them with plain water till they recover. the burnt leaves arent going to recover so stop looking at them right now. they will eventually get worse, dry up and fall off. thats ok. just make sure you pluck em off when they stop being green and are all yellow/black whatever color they turn. what you need to be looking for now is whether its spreading or getting better. dont water anymore till the pot is dry, then water all the way through till theres a little runoff. like 10% of what you put in. continue watching and watering plain water when they dry out. you dont use chemical ferts so no point in flushing. all you can do is wait it out.