Frozen Shrimp Quality Issues: Red/Black Discoloration and Strange Odor

We have observed the following situation with our frozen shrimp: the goods were frozen using the water freezing method, which resulted in the entire box being frozen into a single solid block. All the shrimp are frozen, and their bodies are hard. However, we have observed that some shrimp heads and/or bodies have turned red or black. Additionally, some boxes of goods emit a strange odor.