Hi there. Just soldered my Microdot Phat (which was a Christmas present...) and got it working with a Pi3B on a stock Pixel install.
All installed fine - but on running flash.py I have one stuck pixel (stuck off). I've checked my soldering and it looks OK (and wouldn't faulty soldering lose me a column or a row?) - are there occasionally faulty displays?
I haven't seen a faulty display yet, but it's certainly possible! You're right, though, faulty soldering would lose you a column or a row and not just a single pixel.
What colour display was it?
It's a green display.
You happy to have a go at soldering a replacement on? Removing the display may be a little tricky, but it's certainly possible. How confident are you? :D
If you're up for giving it a go, drop me a PM with your address and I'll get one sent out.
May be a reason to order one of your solder suckers :)