Nz, rattling usually isn't a good sign.
Easy way is to disconnect the speaker from the system and use a 9v battery. If you get a popping sound speaker is working.
I'd start there.
Look for any obvious signs of damage such as tearing to the cone but if it pops you at least know it's working.

 

And now I have wireless Android Auto thanks to this little guy .
I've had one in the CX-5 for about a year now and it works great.



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Nice!
We bought a 2023 Kia Seltos this past December and it doesn't have wireless CP or AA. I thought about getting one of those, but the phone usually needs to be plugged in to charge anyway. The Seltos does have a wireless charging pad, but it's not fast and it's literally 2" from the USB-C charging/data port. I use and there's a short cable just underneath it. I've also found it's easier to scroll through Spotify, my contacts, etc directly from the phone versus screwing around with CP or AA. Guess it depends how long you're in the car for and what you use as to your needs. I drive quite a bit these days.

 

congrats on the Kia!
yeah, I didn't get the wireless headunit up front because well they were impossible to find at the time and I was used to always having my phone plugged in anyways for charging but honestly my Pixel 7Pro has been awesome. Easily makes it through a day and AA has far less battery drain on it now than it used to.
In the daily driver, I agree it is kind of a pain to look certain things up when it connects wirelessly to the headunit and I wish they'd make it easier to still use the phone but I guess that sort of defeats the point of AA?
in the 8, I rarely have my phone in hand. so figured I'd get the dongle. (plus the power cord coming out of the center console always annoyed me.

 

The only thing I can't use on my phone while plugged into AA is the maps. Maps must be done through the head unit. But everything else works as if it's not plugged in.

And I could absolutely see not wanting a cord hanging out of the dash on a nice car. The Seltos is utilitarian. Carries me and my work stuff around. lol Bought it because 10-year 100k mile warranty, AWD, lane guidance w/ adaptive cruise, leather, and turbo model for just under $30k out the door. Already got like 13k miles on it, but about to get a lot more. I've got two 1000 mile trips to make this month.

BTW, if you're near Indianapolis, Slamology is this weekend and Knowledgefest is the 24th. I'll be at both and can get you into either for free.

 

Good work!