Your battery is a heavy duty one containing Zinc Chloride:
https://www.yorkshiretrading.com/pro...k-aa-batteries
I would bet she did not swallow the zinc metal shell but she may or may not have eaten some of the electrolyte. The recommended treatment is Famotidine, Omeprazole, or Sucralfate according to this:
https://www.thespruce.com/what-makes...-toxic-3385501
At this point since it took you a while to re-post any treatment is probably a moot point. A vet tech or senior rehabber can probably advise if any additional treatment is necessary for this highly toxic poison. I assume you checked back in after posting and read my post about liquids and fruits to flush and aid with motility. The treatment in the above link also suggests dilution. I would say it is safe to assume some of the electrolyte probably was swallowed and passed already. In addition to batteries there are many other hazards in a room including but not limited to live lamp cords, painted wood, plastics etc etc. I would suggest supervised playtime no matter how "squirrel proofed" the room is. Nothing is squirrel proof! While I was writing this my Kami who was sitting on my shoulder one minute just ran down and ripped one of my laptop keys off the keyboard making me chase her.
Ember's a very pretty girl!