I seem to be having the same issue, I have installed the drivers and gone through the process of enabling the console on the screen but I am not seeing anything. I imagine the back-light functions regardless of the drivers? I'm not getting anything there with the switch in the on position.
I don't have a ton of time to investigate right now but if anyone else has this issue and finds a solution I'd love to know.
I worked it out, I had LIRC running on the same pins used to drive the PiScreen. I just disabled it, rebooted and bam, the console is now visible and the backlight is on. Thanks for your help. It runs great!