iPhone X gets stuck on guided access mode

I have tried to reboot the device using:

A:

1) Press and release the volume up button.

2) Then, press and release the volume down button.

3) Press and hold the side button until the screen restarts and the apple logo reappears.

B:

1) Press and hold power button and

2) use volume up button or down button with power button to restart

B was rebooting the device when I wasn't on guided access mode but I can't reboot the device when I'm on guided access mode and the device gets stuck.

Please help.

Thank you!