Just today, I received and made a Corne kit with nice!nanos. However, I can't seem to get it actually working. I've built the default ZMK configuration and tried to flash it to the board. It seems to accept the file, exits bootloader mode and disappears from my file manager. But the blue light just blinks, and I can't type anything with it. I know that isn't much more to go off of than "it doesn't work", but I can't see anything in the docs or elsewhere, and I'm not sure where to look next.
Are you able to connect to a host and have the board recognized?
What happens if you connect a USB cable to the main half (usually left)
If the two halves aren't connecting to each other (easily happens if powered on at different times) then they need to be reset at the same time to find each other
The board wasn't recognised at all. I was only trying to use it wired, before trying bluetooth. But after sleeping on it, I realised the controllers are meant to be installed upside down. So I fixed that and now it's working great! In fact, I just typed this comment on it. Quite slowly for the moment, though...
Does it appear to your operating system as a keyboard (when connected via USB)? If it does but you just can't type, check you have the nice!nanos the right way up and/or in the right set of holes (depending on your pcbs, some corne pcbs have multiple possibilities so it's easy to get wrong)