Please follow this instructions to disable automatic startup on each boot.
1) Start your machine
2) Select your system in GRUB
3) Use the arrow keys to navigate to the kernel line
4) Add the argument ‘single’ to the end of the line and press return.
6) Press the “b” key to boot
7) Enter your root password if system ask for it
8) rm /etc/rc.d/rc5.d/S99nxserver /etc/rc.d/rc6.d/K01nxserver /etc/rc.d/rc2.d/S99nxserver /etc/rc.d/rc0.d/K01nxserver /etc/rc.d/rc3.d/S99nxserver
9) reboot
Additionally please follow the instructions here and either attach them to your reply or forward them to issues[at]nomachine.com so we can diagnose why your system didn’t start.
https://www.nomachine.com/AR07K00677