Debian 10 - Power off server using power button, how can I test acpi?

I want to be able to power off my server using the power button on the front of the case, rather than having to login and power it off manually. From my research thus far I believe I have to install acpi to do this, which I have done. I have started the acpi service, and enabled it with systemctl. The status is now "active". However when I press the button, I have no idea if the system is powered off, or sleeping. I suspect it is sleeping and not powered off, because it boots quite quickly again if I press it again. How can I test if acpi is working? I tried to look in the system log file /var/log/syslog, but there's a lot in there and I don't know exactly what to look for.