Computer would not boot after Windows 8.1 update

Hey, guys!

I updated my Haswell 4770K with Asus Z87 Deluxe motherboard computer last night. (It is not my music computer). It was working fine- no visible issues. Been working all day today, and then...

I wanted to restart it because Yahoo Toolbar was not showing up and Yahoo mail was missing check boxes when you want to delete mail- minor thing.

When I restarted, Windows loaded with logo, up to the image that comes right before we asked to put the password in. I wanted to click on the image to proceed to log in screen but mouse would not respond. The mouse was connected to KVM switch between 2 computers. I have lost connection before, so I did not think anything of it. I went on another computer and that one also did not have mouse. I thought- KVM switch froze (it happens once in a while). But keyboard was still working. After trying another mouse, somehow I got that other computer (Windows 8, not updated to 8.1) to restart and now it works fine from the KVM switch.

The first computer with Haswell and Windows 8.1 is not responding to anything. I have now wired keyboard and mouse connected to it directly. If I enter the BIOS, I see mouse working. Soon as I exit and let it load Windows, it goes up to the image before log in screen and never progresses to log in. I did restarted it by shutting down power button, but still- usually that would not make it unusable.
 
I noted that all USB ports appear dead. Like if I put in USB stick, there supposed to be light indicator, but no light coming on. I look in BIOS- there is no setting for USB utilization as I have on my Z77 board where it asks if I want full utilization of USB ports (all usb available during the boot)or partial (only keyboard and mouse). On this computer's BIOS it has "Enable" or "Disable" for all USB ports and all set to "Enable". Something happens to it when Windows loads. My KVM blinking as if computer was off, but Monitors work. Something must be wrong with USB management.
 
I have read suggestion to start from DVD in safe mode and update USB drivers. I am not sure how to start in safe mode and don't want to mass with USB drivers, because then it would definitely not work. Any ideas would be appreciated. Thank you.

I would suspect a basic hardware problem, rather than a Windows problem, since no port responds. 
 
First thought, reset the BIOS (many motherboards have a BIOS reset button on it, others you have to take the CR2032 CMOS backup battery out (with the PC powered off) for AT LEAST 10 Minutes to reset the CMOS (BIOS). 
 
If that doesn't help, break the PC down to only the keyboard and mouse in USB ports, nothing else and try it.

Go to Asus Support. They have new drivers for almost everything. The USB ports may need the newest AI Suite drivers.