DFPlayer mini light goes on and stays on, doesn't play audio

Pretty simple issue to explain, but can't figure out whats going on or what the issue is.

using an arduino pro mini 3.3v. a HC-06 bluetooth module. and a DFPlayer mini. powered by a 3.7v Li-Ion battery. an 18650 to be exact.

all three devices are plugged into the positive/negative rails of the breadboard, which the battery is also plugged into. bluetooth module is plugged into the RX/TX pins of the arduino(RX to TX, TX to RX). the bluetooth module's RX is set to pin 11 through a 1K ohm resistor and TX set to pin 10.

i've tested 4 different DFPlayer minis and they all have this same issue. so it could be a bad batch?

there's a picture of the breadboard set-up.