Hi, welcome on the Yuneec pilots forum.
It depends on how swollen the batteries are (can you posts a picture?) but above all on how much charge they are able to store.
If you have a charger with an indicator of the internal resistance of the battery, you can get an idea of the situation, otherwise the only thing to do is to charge them, check that they do not heat up during charging, then try to make a flight keeping the drone hovering at low altitude without camera (to save it in case of crash... ) and evaluate their duration.