Ways to reset the Windows boot device:
1. Remove the USB device from the port before starting the computer
2. Enter the BIOS and reset the HDD as the first boot device
3. Reset the BIOS with battery removed for 5 minutes or with the BIOS reset jumper moved from pins 1 & 2 to 2 & (previously remove the AC power in both reset methods)
EDIT:
That seemed to me the problem initially but now that I read carefully, I have a few questions:
1. You tried to format reboot and format?... but you don't have a Windows disk (or other stuff) so how did you plan to format and start a fresh installation, or did you just want to use the HDD for storage?
2. If Windows starts to boot and restarts, without a Windows installation disk or USB, your only option is to logon in Safe Mode, pressing F8 right after the BIOS finishes posting and you hear the beep... from the Safe Mode list of options select Safe Mode or Safe Mode with Networking and press Enter. In Safe Mode, Restore the System to revert what ever issue you may have caused.
3. In Safe Mode, install EasyBCD to repair the Windows bootloader.