MP 1,1-5,1 5,1 won't boot after install update

[rainygrass]

3.33*2
580 graphics card on mojave, i believe it's 10.14.4 before install updates
installed 2 updates, 1st was ok
2nd takes a while, at the last reboot, it stuck, frozen, after the boot sound.
no idea, tried reset nvram and several other ways i can find online. no luck so far.
any suggestion? thanks.

 

[h9826790]

3.33*2
580 graphics card on mojave, i believe it's 10.14.4 before install updates
installed 2 updates, 1st was ok
2nd takes a while, at the last reboot, it stuck, frozen, after the boot sound.
no idea, tried reset nvram and several other ways i can find online. no luck so far.
any suggestion? thanks.

Try hold command + R to boot?

It work, re-install MacOS at there (cover on top, won’t erase anything).

 

[MIKX]

3.33*2
580 graphics card on mojave, i believe it's 10.14.4 before install updates
installed 2 updates, 1st was ok
2nd takes a while, at the last reboot, it stuck, frozen, after the boot sound.
no idea, tried reset nvram and several other ways i can find online. no luck so far.
any suggestion? thanks.

rainygrass

I wonder if your cMP is waiting for you to do a cold start whilst holding down the START BUTTON for 6 or 7 seconds until you hear a CHIME so that your bootrom can be updated.

Just wondering.

 

[rainygrass]

thanks for the advise.
solved
it's weird at 10.14.6 update, the machine won't boot into macOS, don't recognize any of the boot disk.
so i followed your advice , hold cmd + R into recovery mode. in this mode, the macOS disk shows up. so i restart the machine again, hold option (alt) again. this time. the boot option just magically shows up again.
then i boot into mojave, everything's ok, system update successful to 10.14.6
restart without holding the option. no
get into macOS by holding option. again. check the startup disk...it's gone after updates...choose the macOS to be my bootup disk.
everything goes to normal now.

so it's this simple, bugs me for several days...weird system update messed up the bootup...that's it.