First you start with your broken doodle.
Flip it over and remove all of the screws on the back.
After you do that you will find that the magnetic strip has come off the slider. get yourself some super glue, pick up the slider and glue the magnet back on. DO NOT glue the magnetic strip to the slider without picking it up. You could accidentally glue it all to the board.
After you know the slider is dry, place it back on the board, put the drawing layer back on, and out your screws back in. That's it! Working again!