IMO there's no shortcut out of a strong guard,just apply the basics.
Keep your posture upright dont look at him look past him keep your spine straight.
Be patient if your posture is right he will struggle to do anything to you with a closed guard and when he opens his guard be ready and work your pass.
Simple in principle but Patience and posture will give you a n opening you just have to be ready to take it.
As for the can opener i wouldnt use it rolling i think its just nasty and is just using pain in the place of technique.