Welcome to the SeeMeCNC Community

Ok,

Soldered the smart adapter myself, and properly wired it (I think). But the screen is showing no life, even after installing the firmware by polygonhell.

I'm assuming it should be on already. And it must be a connection somewhere on the adapter causing the issue? Or do I need to activate it in the firmware before uploading?

seems like your not the only one.

if its completely black then you have the connectors in the wrong headers. If you have it right it should at least light up.

left connector on lcd goes to top of rambo adapter board,
right connector on lcd goes to bottom of rambo adapter board.

I have them wired as you show in this post:
http://forum.seemecnc.com/viewtopic.php ... able#p7035
(last picture shows your wiring)

When that failed, I figured what the hell and wired the other way, screen remained off, but once I connected the USB the piezzo to play sound, and no com connection was made (couldn't connect via repetier).

I'm going to assume it's a bad solder job on a few pins. I'll have to test each pin and find the bad joints. I figured this would happen, but at least my printer is working (kinda, see my build thread for the latest issue).