Okay, can you try the following?
cat ~/.config/serialosc/*.conf
OR
cat /var/lib/serialosc/*.conf
use the latter command if you’ve installed the debian package. you should see the contents of serialosc grid state file, which looks like this:
server {
port = 12988
}
application {
osc_prefix = "/monome"
host = "127.0.0.1"
port = 58986
}
device {
rotation = 0
}
make sure you have liblo-tools package installed. then run the following command replacing <port> with the server port value from the grid state file and <prefix> with the application osc_prefix option value:
oscsend localhost <port> /<prefix>/grid/led/set iii 0 0 1
for example:
oscsend localhost 12988 /monome/grid/led/set iii 0 0 1
the led should light up. if it doesn’t, but serialosc reports the grid as connected, something is not right.
additionally you can run oscdump with the application port as the argument, for example:
oscdump 58986
push some buttons, you should see /grid/key events in the terminal. if you do not - again, something is wrong with your serialosc setup, system configuration or power/hardware.