It's pretty rigid and would be hard to do by hand, but yeah I don't have a ton of options. The kickplate for the cabinets may come off but not easily, so I am going to try to do this through the tiny opening the grate left. I could probably cut it a little bigger if need be. I found these reverse pliers on amazon, hopefully they can just open it up more so more air can escape. If I force it open a bit a ton more air comes out. I'll update once I get the tool.

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https://www.amazon.com/gp/product/B000VH805E/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&th=1