I have a computer that my brother built. I had to purchase a new hard drive, and new power supply for the computer. It has the ASRock B85M-ITX mother board with an Intel i5-4460. When i go to power up the computer after adding the hard drive and power supply and connecting all of the wires, I do not get the ASRock load screen. Also, when i plug in a USB keyboard, it will not receive power. My USB mouse and the USB flash drive that has Windows on it will get power. I am not able to use the keyboard to access the BIOS to install Windows. I have used a USB to PS/2 adapter and used the PS/2 port, and when i do this, i get about a seconds worth of power to the keyboard and it shuts off again. Any advice would be greatly appreciated. I have unplugged everything and rewired it, and it still isn't working. I am banging my head up against a wall here.

This is the video that was used to build the PC by myself and my brother. It worked for him, but isn't working for me.

https://www.youtube.com/watch%3cv=O3F5CGqqA_I" rel="nofollow - https://www.youtube.com/watch?v=O3F5CGqqA_I

The description of the video also has all of the parts that are in the computer.