*** Booting Zephyr OS build v2.7.99-ncs1 ***
nrf52840dk_nrf52840 system off demo
Retained data not supported
Busy-wait 2 s
Busy-wait 2 s with UART off
Sleep 2 s
Sleep 2 s with UART off
Entering system off; press BUTTON1 to restart
ERROR: System off failed