Hello Pimoroni,
I properly connected all boards by tutorial you have on your website, but unfortunately after connecting power via micro USB cable, no snowflakes are shining. After some digging with my voltmeter and continuity tester, I found that it’s caused by misplaced flat cable connector on power board (the smallest board).
If your keen to try and fix it I’d clean as much solder off as possible with solder wick or something. A wet sponge will work if your quick to swipe before the solder hardens again. Then take a needle and carefully lift each contact one by one while melting the solder with your iron. If you take your time and go carefully, you may be able to lift all 4. Then see if you can gently push it so its lined up and solder them back down.