so a lot of your diodes have too much solder on them and not enough on the pad, this means the lead was heated too much and the pad not enough. You may want to reflow them (like all of them) by heating the pad and getting better contact. That could be one issue.
Now with using the DMM to check continuity between pads. The diodes will only show continuity in one direction (because of the diode). So try to switch the leads and measure it then. You should have continuity in one direction only but some DMMs measure continuity differently. Since diodes have such a high forward voltage drop it won't always measure continuity in both directions (my dad's DMM won't; mine will) Try the beep continuity mode.
Another option (and this is what I do) is to set your DMM to diode mode. In one direction (if the soldering has been done right) you can measure the Vf of the diode (about 0.5 to 0.7 V usually). My DMM will only measure the Vf of diodes in one direction, so it's easy for me to see that it's working. Some other DMMs measure the Vf of diodes differently so your mileage may vary.
You can do this to verify that your soldering is good and there's no issue there.
Depending on your firmware, the debounce code can reject a DMM mimicking a keypress. If you're having issues there, try jumpering with a wire that has a blob of solder on each end. Solder is softer and sometimes gives a better result. I could be wrong about the debounce algorithms rejecting the DMM short (in amps mode) as a keypress) but I haven't always had good luck with it.
Ok that shoudl get you started. Hope this helps!
(typed on my skeldon (phantom) bytheway.)
