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.