Once the plastic cover is removed, you can see the metal bracket
holding down the battery in its tray. Remove the two bolts to remove
the bracket. I used a 1/2 inch socket wrench as I forgot to use metric.
I should mention that the plastic cover protecting the positive
terminal should remain covered as much as possible to prevent an
Take care, while using the wrench to remove the bracket bolt, not to
touch the positive terminal.
On hindsight, it might have been safer to disconnect the battery before
removing the bracket.