Spray a slow cooker with nonstick cooking spray. Thoroughly rinse and strain beans, then pour into the slow cooker.
Top with diced onion, jalapeño, garlic, salt, pepper and cumin. Add water and chicken broth and stir to combine.
Cover and cook on high for 5-6 hours or low for 8-10 hours. When done cooking, reserve 1/2 cup of liquid from the slow cooker then drain and return beans to the slow cooker.
Mash the beans using a hand mixer, immersion blender or potato masher. Add reserved liquid as needed to reach desired consistency.