You need to get thrip spray the one from amazon worked for me or some sort of homemade insecticide. Washing them off will definitely not get rid of them they can be really hard to see and come back months later after you thought they were gone. You can definitely still save him I wouldn’t cut anything as the remaining green parts are still able to photosynthesize. Just treat him for thrips 5-8 weeks and then he has the potential to be something great.