Functions instrudction：
Device power on/off:
Power on: Open the back cover, insert 4 AA
batteries, and press the power button for 2 seconds.
Power off: Press the power button for 2 seconds
when the device is powered on.
Car key frequency detection: Detect car key
remote frequency, support 304Mhz, 308Mhz,
311Mhz, 312Mhz, 313Mhz, 314Mhz, 315Mhz,
320Mhz, 321Mhz, 350Mhz, 430Mhz, 431Mhz,
433Mhz, 434Mhz, 441Mhz, 446Mhz, 467Mhz,
868Mhz, 902Mhz.
Button battery voltage detection:
Detect the button battery voltage when connected
to a 2K load resistor (the load test is closer to the
real voltage), supporting a variety of button
battery models, including but not limited to
CR2032, CR2025, etc.
