Hi and welcome to the forum
There are numerous topics on this and thanks for testing the battery
At 3.2V it may take the battery hours just to get going.
- Do you have any LED colour, red would even be good.
- The shop is a bit off with 5V, watch them :). The max voltage will be 4.4V as stated on the battery
- Try new cables and chargers if you have any, even plugged into a PC USB A port will charge after a day
500mA max.
To repeat, when the voltage drops that low 3.2V it can be very difficult to charge, Persevere for some hours and do not ever turn the phone on to test. After some hours just press the power button quickly to see if you get a notification on the screen
It can be laborious as you may have to try different cables and chargers.
An angel may be able to loan you (cable, charger, battery, bottom module etc.)
And before you ask a fairphoneangel to help
- Ensure the USB C port is clean
- Given you have no warranty you can disassemble the phone to check the main contacts and
- Dismantle the bottom module for better cleaning
There is no dedicated charging port, it is part of the bottom module
The core module will cost you 200