Bootable USB for Windows 7 Install
DISKPART
LIST DISK
SELECT DISK 1 or whatever disk # is associated with your USB stick
CLEAN
CREATE PARTITION PRIMARY
SELECT PARTITION 1
ACTIVE
FORMAT FS=NTFS
ASSIGN
EXIT
Then from the BOOT folder on a Windows 7+ install disk:
BOOTSECT.EXE /NT60 X: – where X is the drive letter for the USB stick