Help getting started with Roku devices, including setup, connecting your device to your TV, linking a Roku device to your account at my.roku.com/link, adding channels, subscribing to services, and more.
Below is a pic of the back of your TV. The yellow arrow in the pic points to the HDMI port. I don't see any way an HDMI cable or device wouldn't fit into that port - it's a standard port. Keep in mind, too, that HDMI cable ends are not sized the same on the top and bottom. There's a beveled smaller side, as well as a wider side.
Obviously the cable needs to be oriented correctly. Unless you've somehow broken the connecting end of the stick or the HDMI input on your TV, itself, it should fit fine.
Since you say neither the stick nor the extender fits, then it would seem that you're either trying to plug it in at the wrong location or have somehow damaged the HDMI input port OR don't have the stick/cable oriented correctly. The straight/wide part of the HDMI metal needs to be facing UP and the beveled part needs to be facing down, as shown in the pic below.