Heartbeat module

I have a heartbeat module in my sensor kit, and the programme and serial monitor are working finely, and it is connected GND-S, 5v to middle, A0 to - as it should, but the LED doesn’t light up at all (though smaller lights on the board oscillate with the pulse when the finger is close to the module, only for a few seconds. What should be done?

Without a vendor link for the module and/or a schematic, nothing.

Or translated into polite: please include full details of all hardware and code in your posting as explained in the "read this before posting" sticky-thread