I was thinking it was maybe a thermal overload but it should shut off the light much quicker the second time. It doesn't sound like it's temperature related but I'm not sure what is in the light fixture that would have a timer built in.

lol how much do you want for the broken kessil? i kinda wanna pull one apart as a challenge to see if it can be fixed

I had two out of three Kessil 160s fail. Both would start to occasionally flicker then the only color available was deep blue. Then the light was complete gone. In both cases the internal fan was still working fine. Neither light was ever dropped/splashed/submerged etc.. One failed at 14 months and the other at 16 months. Kessil would do nothing for me as out of warranty. Terrible QC and customer service if you ask me.