What happen here?

Hey everyone,

I have three plants under a sea of screen. One of my plants was doing great but seems to have died quickly.

Can someone look at the pictures and let me know what they think is causing this?

I have thrips. Is it possible this is caused by the larva which is killing my roots?

Temperature: 27 celcius
Humidity: 30%

The pic is not the best sorry. The cola on the left is a good one. The right of that are my dead colas from that one plant.

The bugs could have done it. You could have had a lock out issue. Could be any number of things. We really don't have enough info. Soil? hydro? when was the last time you transplanted? are you ph adjusting? tap water city water? ppms?ect.