After you're done, nudge the solder joints, using as much magnification as you can, to check if they're soldered alright. The joints should be shiny, not dull grey - the absence of bridges is self-evidently important...

If the solder joints are OK, proceed by performing the same checks with multimeter as you did before, making sure there is no continuity whatsoever between the solder joints.

The next step is to clean the solder joints. Use the same q-tip method as before.