Cannot turn off

[Radio999]

When I press or press and hold the power button nothing happens. In the BIOS i selected Instant Off.
The button works fine. And this problem is new to me. The only thing happened is that I removed the MoBo battry for a few days.

[NickS]

Is this independent of OS ?
Tried going into the CMOS, changing the setting rebooting and changing it back ? Allow ESCD/DMI/Configuration data/whatever-your-BIOS-calls-it update/reset