When you are stuck
Stop writing. Read the board again, one group at a time. Look for a group that has only one legal fill left.
Look at your notes. A leftover mark that is no longer legal is often hiding the next move. Erase it, then look again.
You can leave the puzzle and Continue later. You can open a different game for a fresh kind of board. You do not have to finish this one in one sitting.
Do not guess. Every puzzle on DIGIGMA has one solution, so a next legal step exists. You have not found it yet. Repeat the first scans on How to play Sudoku, How to play Star Battle, or How to play Binary Puzzle.