Booting from the USB stick requires that:

If the USB booting seems to fail:

  1. Try connecting the USB stick to another USB port. With desktop computers, using the backside USB ports usually work better as they have more direct connection to the motherboard's USB connectors.
  2. Try different USB port types (USB 2 and USB 3 ports). Sometimes USB 3 ports (usually the blue USB ports) might have problems with the device detection.