Analyzing 4-pin data port to determine protocol
It is far too slow to be USB.  Also, USB is differential and this does not appear to be.  It looks a lot like some sort of serial protocol.  Presuming BK is ground, then it would make sense if W is transmit, R is receive, and BL is +5V power.  

It definitely looks similar to a standard UART serial signal with a baud rate of between 6000 and 8000 bits per second.  I would suggest playing around with the UART decoder settings, especially number of bits and number of parity/stop bits.  Some of those pulses look pretty narrow, though - I'm not sure what to make of that.  

Have you tried looking at the signal with an oscilloscope?  It would be beneficial to confirm the signal levels.  

Also, can you take the top off and try to figure out what is in there that those pins might be connected to?  That may provide some insight into what sort of a signal that might be.