How does systemd timer work?

Question

linux

I understand with systemd timer, there was a problem - timer does not work as it should.
1) I tried OnCalendar=hourly, rebooted, but systemctl status myscript.timerit shows Trigger: ...; 3h 55min left.
2) I tried OnCalendar=00/2:00, rebooted, nothing has changed
3) OnCalendar=*-*-* 0/2:00:00nothing has changed.
What could be the problem?

myscript.timer

[Unit]
Description=simple timer

[Timer]
OnCalendar=
OnCalendar=*-*-* 0/2:00:00

[Install]
WantedBy=timers.target

Answer 1

What should the timer do? As far as I understand, it should execute myscript.service.
Show output please.