Nute burn usually shows up first as discolored leaves, often at the bottom of the plant.
There's 2 main types of nute burn. A systemic burn where you have put too much nutes in the water, and
topical burn. The second kind will show up as splash marks on those places where you splashed nute water for the soil
on the plants themselves.
For the systemic burn you would need to flush well. A secondary or topical burn can be helped by spraying the leaves with
just water. Don't be afraid of over-misting the leaves.
If you can check the pH do that.
Good luck, BigSteve.