Hi, I was scrolling through facebook and my laptop suddenly beeped and turned off. I tried to boot it, but I've just got a white underscore (not blinking) and nothing happened, even the manufacturer logo didn't pop up on start. I tried to boot from USB, but same result. I tried to unplug HDD and plugged USB with live Ubuntu and it works just fine. I thought the hard-drive is dead, so I purchased new HDD from second hand with pre-installed windows, plugged into my laptop and same white underscore. I tried cmos reset, trying to switch RAM sticks. Tried to boot without battery, just with AC adapter but still the same. Fans are spinning, I can feel it and hear them. I don't really know what's wrong.
I had a similar problem with an HP laptop. Turned out the drive was OK but the cable connecting the drive was defective. You may have the same issue or the interface hardware on the motherboard may have failed. Boot to Ubuntu with the HDD connected and see if it is visible to Ubuntu (I'm not much good with Unix so I don't know how to do this off hand).
I would be skeptical if a HDD with someone else's Windows install would work in your machine. Part of the install process is to tailor the OS to your particular HW. Boot actually works differently in some machines also depending on the BIOS. Trying to get one of the hard drives to work with Ubuntu may point you in the right direction.
Generally "hot plugging" HDDs only works if the hardware is designed for that (like servers). It won't work with most hardware. I assume you've changed the BIOS setting to make USB the first boot selection.
I tried what you said, I can't boot from USB when HDD is connected although USB is first boot option in BIOS. I tried to select USB from boot menu but still I've got the same white underscore. Laptop shows that white cursor maybe for 10 seconds and laptop restarts.