Leon and Helena. Chapter 5. final boss (Resident Evil 6)

How to kill the boss? Lightning rod can't pick up, he is literally rooted in the ground (standing, not lying). Should the boss cut off the leg (paw) as he picks up another zombie and halitsa. The process is endless. In the end, the game came to a halt, it is impossible to pass on. It may, of course, in my stupidity, but I just don't know what to do. Please help!