How to repair or replace the micro usb port

well i believe you already started doing it yourself, if the solder contacts on the connector look like it has a solid connection to the circuit board then that shouldn't be the issue, and you should look at the contacts that the cable connects to, to see if anything in there looks out of place, if not then try cleaning the connections with isopropyl alcohol. You can use water but that will cause corrosion creating problems in the future if you can get to them, if cleaning doesn't work then i'm afraid that you will have to get a higher voltage or multi-voltage soldering iron and buy a replacement micro usb port .