Filing this quickly while investigating. It seems live images from 2015-07-11 onwards do not boot, neither in BIOS nor UEFI mode. BIOS boot hits syslinux menu then silently loops back to it when you try and boot; UEFI boot shows an error indicating that initrd0.img does not exist. A new dracut was built on 2015-07-10, so I rather suspect that's the problem, but I'm looking into it now. Marking as an automatic blocker: "Complete failure of any release-blocking TC/RC image to boot at all under any circumstance - "DOA" image (conditional failure is not an automatic blocker)"
<bcl> adamw: probably. things now need dracut-live <bcl> I'll do a new rawhide build at some point today/tonight.
OK, this should be fixed for the next round of nightlies - we needed to add dracut-live to spin-kickstarts fedora-live-base.ks: https://git.fedorahosted.org/cgit/spin-kickstarts.git/commit/?id=cf118093e3294b264d60d830e78cc39aa8f097c9
This bug appears to have been reported against 'rawhide' during the Fedora 23 development cycle. Changing version to '23'. (As we did not run this process for some time, it could affect also pre-Fedora 23 development cycle bugs. We are very sorry. It will help us with cleanup during Fedora 23 End Of Life. Thank you.) More information and reason for this action is here: https://fedoraproject.org/wiki/BugZappers/HouseKeeping/Fedora23
This is fixed.