HiLetgo USB Logic Analyzer Device with EMI Ferrite Ring USB Cable 24MHz 8CH 24MHz 8 Channel UART IIC SPI Debug

Like 309 said, the J12 is a usb interface and might be interesting. The J13 might be a programming interface (In-Circuit Programming ClocK and In-Circuit Programming DAta?). It's also possible the chip in the middle has UART pins somewhere along the edges. Pop the heatshield off and see if you can find a data sheet on it. 309 kind of gave you the finding rundown, but just to rephrase. GND is easiest to find. Generally any of the shielded stuff. Put a multimeter on two of them in continuity and see if it beeps. THe areas around the screw holes, the USB shield along the bottom, the chip shield, etc. Tx is usually the next easiest to find as it'll fluctuate. It can be hard to notice on a multimeter though if it's brief, easier to hook up a logic analyzer. VCC and Rx I usually just have to guess at. For tools, maybe a USB pigtail for the J12. A cheap logic analyzer helps find the RX and TX, and a USB to TTL to actually communicate. For resources, https://www.youtube.com/@mattbrwn and https://www.youtube.com/@D1gitalAndrew

What you’re describing is typically called a “logic probe”. They’re still a thing, but becoming increasingly rare as signals get faster. This is an example of an extremely cheap logic analyzer. https://www.amazon.com/HiLetgo-Analyzer-Ferrite-Channel-Arduino/dp/B077LSG5P2

https://www.amazon.com/HiLetgo-Analyzer-Ferrite-Channel-Arduino/dp/B077LSG5P2