Heat olive oil over medium heat, in a large skillet. Add chopped onion and garlic, sauté until softened.
Mix in chili powder, cumin, paprika, salt, and pepper. Cook for 1-2 minutes until fragrant.
Add shrimp to the skillet and cook until they turn pink, usually 2-3 minutes per side. Remove the shrimp with a slotted spoon and set them aside.
Warm the flour tortillas in the microwave for about 20 seconds or in a dry skillet until pliable.
On each tortilla, spread a spoonful of refried beans, followed by a portion of the cooked shrimp and a sprinkle of shredded cheese.
Fold in the sides of the tortilla and then roll it up tightly, securing with toothpicks.
Heat vegetable oil in a skillet to 350°F (175°C). Carefully place each chimichanga seam-side down into the hot oil and fry until golden brown, turning as needed.
Remove chimichangas and drain on paper towels.
Serve hot with sour cream, salsa, guacamole, chopped cilantro, and lime wedges.