The reason your USB loader often fails is that the device is in the wrong mode. To force it into the correct state:
This specific loader is tailored for the "s-320" variant. Using a loader meant for the "s-856" or "s-606" on an "s-320" will result in a failure to initialize the USB port. e5573s320 usbloaderbin work
How to Fix a Bricked Huawei E5573s-320 Using usbloader.bin Huawei E5573s-320 The reason your USB loader often fails is