So, I'm thinking the charging port is broken, but let me know if you have any ideas..
The phone stopped connecting to my PC via USB, and is only charging, and there is no prompt where I can change it to MTP / Transfer Files, I did however change it in the Developer options, to set the Default USB Configuration, and I also ticked the box for USB Debugging.
It doesn't seem to work to fast charge as well, I tried several different cables and chargers, works fine on my other phone, how ever, it works to Super Charge for some reason with the Super Charger.
I tried to follow some guide that told me to open the Phone App, and press something like *#xxx#*, didn't work either.
I also can't update to a new software version, im stuck with an update from September 2021, and it says "your current version is not supported", I don't know what to do... 😞
I have now made a factory reset, and it didn't work either, so it has to be a faulty charging-port, right?
At first, it would only charge if you wiggled the cord around to find the right spot. Then I started having to wrap the cable around the phone to put tension on the end of the charger, holding it in place, which prevented the use of the device while charging. Finally, it stopped taking charge altogether.
Since it was no longer under warranty, I haven't yet had it repaired to confirm the issue, but my experience sounds like what you describe.
You're also not alone; this was a relatively common issue with the entire line of S20s, although I'm not sure if any extended warranty or device repair is available or if Samsung even formally acknowledged the problem. 😕