Okay, so, I currently have a HP ProBook 4540s and I am typing this message with a macbook pro 13 inch retina display. (2015) OS X El Capitan. I am in a very tough scenario. I had to reformat completely my HP laptop, and during the process, for 24 hours it was stuck at 36%, so (stupid me) I turn it off and back on in attempt to cancel the process. This gave me the message "An operating system wasn't found". I immediately looked for help, and I figured out to format windows 10 install to a USB boot drive. I had done that, and it had the setup files and everything in the USB. However, I cannot figure out how to boot the USB to run the installer. I also (stupid me again) ripped off the serial key not knowing what it was when I first got the computer (3 years ago), so I cannot contact HP support. What do I do? And If booting won't work, is it possible to create a HP recovery usb on the mac?