FTL is typically "fired too long". In my experience, this is because the kiln struggles with trying to maintain the top temperature you have programmed, and it eventually errors out.
I get this error if I try to do a screen melt in my Fusion 14, which is a 14" brick kiln on 120V. That is a lot of thermal mass to try to heat off 120V. You are looking at a similar situation with the Caldera, which, based on what I am seeing in the specs is 14x12 and 120 V.
Turn it on again and keep going
(note: if you have any concerns about the kiln malfunctioning, consult a trained professional, which I am not
). You may also be able to do a pull at 1600 deg F, where you might have a little better success with the kiln staying on.