Also.. what's the best way to clean out that solder in the pi?

I think the only one that might be a pain is that first pad: DIN. The second pad isn't used by the Null 2 as far as I can tell. The rest should be good to go as long as the Pi is Ok - does that sound right?

I used the practice boards from Helder. However, I think those messed me up - because the testing pads and the GPIO holes kind of made sense when lining up. However the Null 2 test pads and GPIO holes don't follow a similar pattern and I overreacted when I wasn't getting tone from my multimeter and ...

So.. I'm new to all this, and I'm pretty sure I ruined both my pi zero and my null 2 board in trying to solder the pi onto it. Any tips or tricks or any ways to salvage this? I literally couldn't get the second pin I tried soldering to connect. Pretty frustrated. Now they are taken apart and pretty ...