Recently I encountered a problem of ‘host key verification failed’ when I was trying to connect to host while being on the serial console.
debug mode says ‘/dev/tty’ does not exists, while it does.
but problem is : you are on serial console which is /dev/ttyS0 not /dev/tty, so now you can guess what to do :
create a symlink of /dev/ttyS0 to /dev/tty
ln -s /dev/ttyS0 /dev/tty
or setup password less remote login.