Ok, so I managed to pull apart all the speakers and disassemble the entire store display. I'll post a few videos later showing this. First thing I did was crack open the speakers to see what was in there. It turns out the largest speaker ("Get Together" model) had a dedicated amplifier board that was put in there by Data Display. I will show this in a YouTube video later. For now, I've posted a screenshot from my video here (I've attached both zoomed and larger photo showing the amplifier board in the largest speaker below):

So those buttons on top of the speaker do nothing, the buttons basically all seem to connect to the ground plane. I've noticed this also with the ports at the back of the speaker... just a PCB with everything either shorted or completely open when necessary (to prevent someone from plugging in a power adapter and shorting it).
From what I gather, the micro's on there are as follows:
TAS5709 5AW G4 APXQ (20 Watt Digital Stereo Amp):
https://www.ti.com/lit/ds/symlink/tas5709.pdfAKM 5358AET 4S610 (A/D converter):
https://media.digikey.com/pdf/Data%20Sheets/AKM%20Semiconductor%20Inc.%20PDFs/AK5358A.pdfST 78259 ... PHL 619 Y (ST Micro): not sure what this part is
My guess is the A/D converter takes in the 3.5mm phono input and converts it to digital, since the TAS5709 will accept only digital input. Then it gets amplified and fed to the speakers. I'm not quite sure how the STMicro part fits in with this, maybe someone can explain.
I also opened up the Chant Mini BT and found that it contains the original Marley PCB!!!! What Data Display did was just connect 5V microUSB across the battery terminal pads where the battery would be... and soldered the 3.5mm audio cable in to the PCB on the pads that are for the 3.5mm input (female) phono port. But something is up with the firmware or they disabled something else.
I can power it by using the actual microUSB input port on the unit since it connects to the PCB itself, so I was able to get rid of that extra power cable running out the back. Same goes for the 3.5mm" line in... I can use that on the PCB itself. I also get a Bluetooth detection up and my phone is able to see it but it won't connect when it tries (fails with some error). Also the power button doesn't seem to turn it on or off (it is on the minute I plug it in). As well, when pressing the bluetooth button, no LED flashes, there is no light at all... nothing, no sign of life. So this PCB seems to a modified or crippled version of the original PCB..... UNLIKE the PCB that was found in the largest speaker ("Get Together") which is a dedicated amplifier-only board made by Data Display.
I haven't bothered opening up the middle size speaker (Chant). I doubt I will get any further with it and I don't want to ruin it. However, I did find a neat trick.... because the Chant Mini has the audio cable (male end) just hooked in parallel with the audio input port on the PCB (female), I am able to "daisy chain" the Chant and Chant Mini and have them play the music together! I plug the MALE cable from the Chant Mini into my phone, and then plug the MALE cable from the Chant into the female "input" port (which is now acting as an output)... Hence the single source is now feeding both Chant Mini and Chant speakers!

I will have to show this in a video at some point. Anyways, not a complete disappointment. Nice speakers, but no bluetooth functionality, no battery. Just monitors basically with no volume control (maxed out). I can plug into any mains source, plug in any sound source via the 3.5mm phono and away it goes. I could try to add extra features... for example, it would be trivial to install a radio, MP3 player, and other stuff inside the case of the "Get Together" to give it many other selectable sound sources. Perhaps even a battery/charger circuit. Fun project for another day.