Desktop Wont Boot ?

[Robert11]

Hi

Have a 4 yr old mac desktop.

Tried to update to the latest OS, and now it won’t boot or start (anymore)

Just hangs up.
Tried everything I can think of to get it to normally boot, but always hangs.

Would be most grateful for any suggestions.

BTW: what’s the “normal” lifetime for these desktops ? Always has been left on.

Thanks,
Bob