There are two 2.3 cm-long magnets along the right edge of the screen. Don't insert your opening pick more than 2 mm to avoid damaging the screen in these locations:

The first magnet begins 1.9 cm from the top of the iPad.

The second magnet begins 2.9 cm from the bottom of the iPad.

Everywhere else, don't insert your opening pick more than 5 mm.