So they charged you a paltry FOUR HUNDRED DOLLARS TO REPLACE A BATTERY
AND RUN A BENCH TEST???
I know, a life is worth more than $400, but frankly that seems like gouging to me. Fifty bucks for a half hour of a tech's bench time, fifty more for a battery, fifty more to replace the case that they probably glued shut.
$150 would be more than adequate, $400 is simply unreasonable for a battery change. Check out the "406 EPIRB" sales prices right here on Sailnet, for that money
they should have sent you a fruit basket and theatre tickets as well.
Then of course, the question is if you take this to a USCG station for actual testing--is the unit going to work, and identify your vessel correctly?