No you really should wait at least 1 week before attempting again, each time. Trying as often as you are is probably stressing him out more. 30 mins for a fuzzy may be too long in hot water. How do you thaw them out? I usually pull my rats/mice out of the freezer the night before and keep them in my fridge until feeding time, then put them in hot water. Hoppers are only in for about 5 mins before they are up to temp, adult mice about 10 mins, rat pups about 10 mins, weaned rats go for about 15-20. You may be over heating them. Make sure you wait another week before attempting.