Windows fastboot needs the libusb drivers installed correctly, using instructions and links provided in the debricking threads. Fastboot mode does not change what is on the screen. It only changes the USB VID/PID that a usb utility (or device manager) would show you.
There is no such thing as "totally turned to a brick" unless you have a serious HARDWARE failure. You would know this if you read the stuff I told you to read. Go read it. All of it. Including the linked threads. Do it. Do it now, before you are tempted to ask another frequently asked (and answered) question. Thanks.