I would assume the original Nova takes the same battery as the Nova Pro since the Note and the Note Pro seem to take the same battery. You can usually find such batteries for sale on Aliexpress. That's where I got the battery to replace the one in my Note Pro.
Here is one listing for the Nova Pro battery on Aliexpress:
https://www.aliexpress.com/item/1005...9765040f08ed-4
You also may want to check out the following thread. Even though it is in relation to the Note Pro, it should give you an idea of how to open up the Nova and what to expect:
https://www.mobileread.com/forums/sh...d.php?t=339908