Battery change problems

[Waynemarlow]

Hi, just changed my XT's Battery after it has failed ( 2014 car ) mainly from being run flat from a boot closing problem ( which Subaru wouldn't honor 4 weeks out of warranty despite it being a problem since new ). Now when I move the car warning beeps are coming from the N/S rear panel. No warning lights are on the dash and its similar to a previous problem when the bonnet opening sensor was disturbed when having a front window changed. 

Any clues how to solve the problem ?

PS really peeved badly and feel let down by Subaru over the boot closer problem, not happy at all having to front up £ 600.00 notes for a replacement motor.