A quick search for "EPT 804560P" returns nothing, you could:
* try to contact the manufacturer (I guess [link|https://ept-battery.com/|EPT battery]) and ask for replacement resellers/specs for a compatible spare part
* buy a 7.4V 2000 mAh battery with the same shape and connector
Above all, as the battery is swollen, please treat it very carefully, see also guides on iFixit: [[What to do with a swollen battery]]