How can I get it to work?

Hi, I'm trying to control one ESC on my Teensy 4.1. I changed ESCPID_NB_ESC to 1 and my HOST_DEV_SERIALNB to the SNB of my Teensy. Unfortunately I can't get the ESC to boot. The Error code in the Linux Terminal is sometimes -10, sometimes -9. I don't know what that means. Can somebody explain?