When is the jack dead, and what happens to a dead end?

Live jack in the ditch (law 18). A jack moved by a bowl in play into the front ditch within the side boundaries of the rink is live. Its position is marked with a white indicator (not more than 50 mm wide and 100 mm high) placed vertically against the face of the bank or on top of the bank in line with the jack.

Dead jack (law 19.1). A jack moved by a bowl in play is dead if it:

• passes completely outside the boundaries of the rink;
• comes to rest in any hollow in the face of the bank; or
• comes to rest less than 20 metres from the centre of the mat line (measured in a straight line to the nearest point of the jack).
  It is not dead if it comes to rest on top of a toucher at rest in the ditch, or on top of bowls at rest within the rink (law 19.2). The skips (or opponents in Singles) decide, and ask the umpire if they cannot agree.

Dead end (law 20). A dead end is not counted as a completed end. It is replayed in the same direction unless the skips (or opponents in Singles) agree to play the opposite direction, and the player who played first in the dead end plays first again.

Rebounding jack (law 21). The end continues if a jack at rest on the rink is driven against the face of the bank and rebounds onto the rink, or a jack at rest in the ditch is moved back onto the rink by a toucher.

Source: World Bowls, Laws of the Sport of Bowls Crystal Mark Fourth Edition, laws 18 to 21, https://www.worldbowls.com/wp-content/uploads/2023/05/Laws_of_the_Sport_Fourth_Edition.pdf