To find the SysRq in your system, normally PrtSc, run:

journalctl -f

And then press keys Alt Gr + PrtSc + h that will print in the logs something like:

the Right Alt GR only works printing the help

kernel: sysrq: HELP: loglevel(0-9) reboot(b) crash(c) terminate-all-tasks(e) memory-full-oom-kill(f)...


create /etc/sysctl.d/99-sysctl.conf with:

kernel.sysrq = 1


sysctl --system


To reboot system in a crash run:

Alt + SysRq (Hold down) + R, E, I, S, U, B

R: Switch the keyboard mode
E: Send the SIGTERM signal to all processes except init
I: Send the SIGKILL signal to all processes except init
S: Sync all mounted filesystems
U: Remount all mounted filesystems in read-only mode
B: Reboot the system

To only reboot:

ALT + SysRq + b