Phone works when plugged in but will not charge

My Samsung Galaxy S5 all of a sudden started making the "plugged in" then "not plugged in" set of sound every few seconds. Now it no longer shows the charging symbol when plugged in, and the battery does not charge either when turned on or turned off. When turned off and plugged in, it shows the lightning bolt symbol for a few seconds, then switched to the yellow exclamation point battery sign.

The big twist: The phone works fine when plugged in, and the battery does not drain while plugged in. Therefore, the charging port is clearly still functioning and powering the phone.

Testing rules out the wall socket, the adapter, the charge cable, the battery, and apparently the charge port as points of failure. I have no ide what else could have failed. Help!

Tests:

Tested with known good adapter (verified with different phone)

Tested with a different, know good battery

Tried with multiple known good wall sockets

Tried to charge while turned off

Cleared both charge port and charger pins with compressesed air

Visual inspection (no bent pins)

Soft reset

Reboot