Your tee shot on the 4th ends up in the red penalty area on the right and you decide to play it but unfortunately it ends up still in the penalty area.  What are your options if you do not want to play the ball as it lies?  Under penalty of one stroke you can:

• Take stroke and distance relief by playing from a relief area based on where the previous stroke was made in the penalty area, 4th shot
• Take lateral relief, the reference point being where the ball last crossed the edge of the penalty area, 4th shot
• Take back on the line relief by dropping a ball in a relief area based on a reference line going straight back from where it last crossed the edge of the penalty area and the hole (an unlikely option at the 4th in Bearna), 4th shot or
• Play from the tee again, 4th shot

If you choose the first (stroke and distance) option, drop the ball and then decide NOT to play the dropped ball, for an additional penalty you may take lateral relief, back on the line relief or play again from the tee, 5th shot

All of these options are described in Rule 17-2, Options after Playing Ball from Penalty Area.  You cannot declare a ball unplayable in a penalty area, you can only proceed under the penalty area rule.