Zevachim 35 - Temporary Rejection
If a person whose service is invalid nevertheless takes a small part in it, the service can still be rectified, continuing with the people fit for service. But why should this be possible? We have a principle that a sacrifice that has become temporarily rejected is rejected forever. For example, if on Yom Kippur one of the two goats died, the second one can never be re-used, even after we bring another goat.
The answer is that either the Sage who authored the rule does not subscribe to the principle of "once rejected - forever rejected", or that a rejection that can be rectified by our hands - like in this case, where a fit person can take over - is not considered a rejection at all.
If, while slaughtering the sacrifice, one has a wrong intent about eating, and plans to eat in the wrong place or after allotted time - but what he plans to eat is not usually edible, such as the hide, or is not really the meat of the sacrifice, such as the gravy, or he plans to eat less than an olive's volume - the sacrifice remains valid.
Art: Jan Steen - Grace Before A Meal 1660