Texecom have a hold off disable mode for installation and testing, it's likely the bell was not functioning correctly due to this.
If the hold off voltage is removed, the bell should sound out strongly for it's hold off time (15 mins) and then stop. It should also do the same if it's lid is opened, or a negative is applied to trigger terminal.
It's also possible for the battery to be disabled, not connected or wired incorrectly at installation (seen this fault many times) so this maybe the case if you've swapped the battery like for like.
It could equally be possible the bell is not functioning correctly as pointed out way back in the thread, is very unlikely but a possibility you shouldn't rule out.