Hi,
I would not use a bloated battery!!!
If you want to take a picture I would recommend to use a camera or an other smartphone (maybe a friend can take the pictures).
On a flat surface a bloated battery is easy to spin around (=“Spin test”). Check the manufacturer name on your battery. Some batteries from “Fenghua” tended to start bloating:
Here you will find some more info on that issue:
As far as I know bloated batteries from “Fenghua” are a warrenty issue and are replaced for free. You should contact the Fairphone support team. You have to send them the serialnumber of your bloated battery that they can check if it is a warranty case.
The batteries are on stock, so you should get a new battery soon:
https://shop.fairphone.com/en/fairphone-1-battery