Hi Welcome to the forum.
-
You can do a battery test by dialling
*#*#66#*#*then Service test > TestSingle > Battery status check. -
I would advise against calibrating as described via the link in the previous post as you can’t charge it yet. For example The iFixIt site recommends
- Charge it to 100%, and keep charging it for at least two more hours.
- Use your device until it shuts off due to low battery.
- Charge it uninterrupted to 100%.
-
Try and find another person with an FP3 to see it will work in their phone etc. maybe you can find a fairphoneangel near you to help
-
That the charger and cable work elsewhere is no a guarantee either will work with the FP3 even if they have done so in the past.
-
You may like to check the FP3 usb port for debris
-
It could be poor contacts between the modules, you may like to check that.