10.9.3 update is not installing on my macbook Pro 13" Retina

Question

I have a MacBook Pro 13" with Retina display, late 2013 model (high end specs).
I tried to update from 10.9.2 to the latest 10.9.3 versio, downloaded the update and the computer asked to restart to install the update, but it got stuck with nothing on the screen and the menu options of the software update.
I kept it for a very long time with nothing on the screen and then held down the power button to shut off then start again.
The computer starts normally, but wifi will not detect internet from any hotspot I have, until I switch wifi off then on again.
Still my machine is 10.9.2 and everytime I try the update I get the same thing.
I tried the combo update (out of the Mac App Store), but the same thing happened.
Anyone can help?

Answer 1

Please read this whole message before doing anything.
This procedure is a diagnostic test. It’s unlikely to solve your problem. Don’t be disappointed when you find that nothing has changed after you complete it.
The purpose of the test is to determine whether the problem is caused by third-party software that loads automatically at startup or login, by a peripheral device, by a font conflict, or by corruption of the file system or of certain system caches.
Disconnect all wired peripherals except those needed for the test, and remove all aftermarket expansion cards, if applicable. Start up in safe mode and log in to the account with the problem. You must hold down the shift key twice: once when you turn on the computer, and again when you log in.
Note: If FileVault is enabled, or if a firmware password is set, or if the startup volume is a Fusion Drive or a software RAID, you can’t do this. Ask for further instructions.
Safe mode is much slower to start up and run than normal, with limited graphics performance, and some things won’t work at all, including sound output and Wi-Fi on certain models. The next normal startup may also be somewhat slow.
The login screen appears even if you usually login automatically. You must know your login password in order to log in. If you’ve forgotten the password, you will need to reset it before you begin.
Test while in safe mode. Same problem?
After testing, restart as usual (not in safe mode) and verify that you still have the problem. Post the results of the test.