Number one thing to do in a troubleshoot is to re-flow.
Use a conical tip and beware of too much heat. Have some extra solder handy while doing this for when it is needed. You want to re-flow the solder so it is a complete joint and not a bulb on top or a dull joint that has gaps. So many issues have been solved by re-flowing. Clean your soldering tip often.
To aid you I would do every joint I marked in the photo at the very least. Personally I would touch them all up.
