Reflowing all your solder joints is the correct first step, so good job there. (
This post is all about your problem, if you want to go a little deeper and haven't already read through it.)
Since you've already done that, we definitely need to see photos in order to help you more. Beyond those tips, we'll need to see some good, clear photos to help you troubleshoot. Show us both sides of the board and all your off-board wiring. Taking the photos in a well-lit area is much better than using the flash. Make sure you're holding your phone or camera really still to avoid blurriness.