Peroxide doesn’t work on trich. Doesn’t even help. You’re just weakening the surrounding mycelium, allowing the trich to get a better foothold. Trich is not a surface only contam like cobweb, and is in the substrate itself. Continue to cut chunks out and salt if you’re bent on seeing this through. Pray that the other two don’t have green patches within the next couple of days. The salt is going to draw a LOT of moisture out of the substrate, so make sure to soak up any pooling water.
Trich sucks, but it happens. Eventually you’ll get better about cutting your losses. Always have more spawn going for situations like this one so you’re not starting 100% from scratch when it happens again.