I followed the instructions by Dell for my Inspiron 3847 reinstalling Windows 10 using USB media. I put in my media that I created in the USB port before I restarted my computer.
It says: On the boot menu under UEFI boot, to select the media type (USB or DVD), but that was not an option. The list said: BIOS set up, Diagnostics, or change boot mode settings. I wasn't sure where to go from there.