Yes, the could have possibly stumbled upon it, but I think it far more likely that crystals scattered around were more of a sacred object as opposed to being used for anything electrical. "Cut and polished" is taking liberties as well. Get a large geode and you can pull crystals just like that out of them that are highly planar. As for the wire, I suspect a lot of jewelry used wire.
In general, anyone with the knowledge to build a "radio" of any kind probably wouldn't store it inside a carved stone turtle. It would be like storing a laptop in a cave.
Nightwolf wanted to know (and I haven't had time to look it up today)
"What did Turtles symbolize in Cambodian/Hindu or Buddhist traditions?"
He said that might give a "hint" to their purpose.
He said if "we found something like that in a Norse Find and the stuff was inside of Stone Ravens (Odin's Messengers) that would be a hint that maybe if it looks like it could be a communication device, that is at least work seriously studying and considering."
He also said that doesn't mean that it was it is, it could have been used for an "Oracle" to "Communicate" with the Gods - aka a slightly unusual actual "ritual object" despite that being the archeologists way for saying for the last 200 years,
"If we don't have a clue, it must be a ritual object and/or a phallic one."
Another real-life example the Bagdad Battery was found in the ruins of was obviously a medical doctor home, they found his instruments and other items still enough "there" to make that rather clear. A bit of talking to local people (even today) found that a local "cure" for arthritis was to have the patient stand on an electric fish that give off a slight charge and live in the waters nearby. The use of minor charges of electricity to deal with pain has even been used in pain control experiments today and you can buy modern versions of "electric" fish from some health sites.
So while originally it was thought the battery was used for electroplating, and jewelers may have done that, but the only one found so far was in a doctor's "office" so was probably a "medical device."
Again, why didn't they go on to make lightbulbs? Well if you do a social history of modern electricity, for the first decades after it was discovered, it was used mostly for "medical cures" for a given form of cure, and entertainment (like the tiny steam engines for rich men's toys in Alexandria).
It took a couple of centuries to really make it very practical for daily use, especially for things like lighting; once that happened the technology took off like a rocket - but it might not have, or at least not nearly as quickly or become so widespread.
But I did mention the high likelihood that this may just be "ritual stuff" or jewelry makings, it just that it isn't impossible that it might be very simple radio or signaling technology; finding out more about turtles in context would help.
Especially if say we see turtle designs on the clothing of dancers that look like they are wearing clothing decorated with turtles or something.