Cannot close trunk unless window is open - cabin pressure release valve on 2021?

[StevesExpedition]

Hi all,

I have a 2021 XLT and I think I have a stuck cabin pressure release valve. The trunk will not click shut when closing unless I have a window/door open

Can anyone help with the location of this? Is it behind a tail light? I'm hoping its an easy at home fix rather than a trip to the dealer.

Any help appreciated!

Thanks!

Steve