I recently started ordering parts to build a new gaming rig. Got everything ordered except a monitor and new SSD so i decided to just take the HDD from my laptop and install it in the new desktop and use the TV as a monitor until the other parts come it. Got everything together fine and started it up. The keyboard worked before windows loaded (i had to press f1 to cont normally with boot) but one it got to the password screen the keyboard wouldn't input anything. So I powered down the computer made sure that the front panel USB ports were plugged in and everything was fine. After this point I could no longer get any display from the computer. I tried taking out the cmos battery checked the ram tried the other video card port everything I could think and nothign helps
It is possible that the reason the keyboard didnt work the first time is that the drivers were being installed for all the bits in the new computer before the machine could use the keyboard (ie the keyboard drivers were not in place at the point when you turned it off). It can take a few minutes for a transferred hard drive to work - if if is going to work at all!.
If you had important data on your drive then try installing it into the original machine and see if you can access it.
If I understand you correctly, you can still see things happen on your new build until the Hard drive takes over (can you see a "Splash" screen showing the motherboard or graphics card manufacturer? With the hard drive removed, try starting the machine. Do yo get a message sying no bootable devices are found? - or is the screen blank?