My eyes have lied to me more times than I can count, and my last build was basically a solder bridge convention that I kept calling modern art. I spent twenty minutes chasing a short with a multimeter before figuring out the whole problem was two joints kissing each other under a blob of flux. A loupe lives on my bench now and it has saved me way more grief than the ten bucks it cost. What gets me is how the bridges hide in plain sight, you stare at the same row ten times and your brain just fills in what it expects to see. My eyesight is not getting any younger either, so anything past 40 pins and I am reaching for the glass. Cheap lesson learned, check the board with glass before you fire it up, not after it starts acting up on you.