I've got the typical problem that OSX can't shutdown/restart normally. I'm on El Capitan but it happened in the past with Mavericks etc. Don't know why they can't fix this...
Anyway, now I want to install El Capitan update 10.11.3, the final step is it wants to restart the system.
I click the 'restart' button but the restart fails.
I can hard boot by holding down the power button... but then the update doesn't finish its install - it still says I need to restart if I go into App Store.
Restart or shutdown from the Apple menu don't work.
I tried a
shutdown -r now from Terminal... this successfully restarts but the update still 'needs restart' when I go back in after booting.
MacBook Air (13-inch, Mid 2012) El Capitan 10.11.2