After soldering all the components and writing a test program to display 012345678, we notice something bad. The first two digits are off. Nothing we try in software changes that, they do not want to light up at all.

And this is how we find out A6 and A7 are input only. They are the selection lines for the first two digits. They need to supply 5V and cannot do so.

Also, the multiplexing algorithm is wrong, 8 is brighter

Time for a quick instagram post while we think how to get out of this mess.

https://www.instagram.com/p/Bdlqbo-n48G/