Hey I wanted to install linux on SP4, but it doesn't seem to recognise any usb! I tried it with a usb which have a windows image in, but still it doesn't work. A point is that, my TPM and secure boot are disabled but when i try to enable them, they can not be change! Seems that you can't change security system anymore. I tried to boot from usb by hold down the volume button but that doesn't work either! Can any body help please?