Thank you for your query,
Ingestion and swallowing of batteries and battery material is dangerous as the material inside is acid and chemicals which lead to burns in oral cavity and in the esophagus
and lead to strictures.
The small round batteries due to accidental ingestion lead to damage to esophagus, stomach and gut due to its electrical activity and caustic action.
So consult your Pediatrician
for the examination of oral cavity to look for any ulcers and signs of acid ingestion.
In the future also be careful with batteries and foreignbody ingestions.
Hope I have answered your query.