You should have some experience with Magic Lantern before attempting to run nightly builts.
Pull the battery, pull the bootflagged card. Insert clean, unflagged and freshly formatted card. Insert battery.
It doesn't boot? Not Magic Lantern's fault!
Does it boot? Hooray!
Pull the battery, pull the bootflagged card. Insert clean, unflagged and freshly formatted card. Insert battery.
It doesn't boot? Not Magic Lantern's fault!
Does it boot? Hooray!