Apparently, the unit's failure was my fault. Here is the response from Ultralife. You be the judge.
"hello
we have received the unit back.,
under inspection the technicians have determined this would not be covered by warranty. There is obvious signs of exposure to water inside the unit. They have determined it was the reason for shorting out the bulb. From inspection they say it seems to be from a cracked sleeve.
For repair it would require a new sleeve, bulb, ballast and grommet. We would not charge any labor.
If interested please let me know"