Prgramming question for MDFly AU5016 MP3 player module

Hello Everyone,
I have used the Tenda TDB380 MP3 boards with geat success, but thought I'd try MDFly's AU5016 MP3 board and I cannot get it to work with Arduino. Here's the datasheet.
http://mdfly.net/Download/Module/AU5016.pdf

I'm trying to run in Serial mode. I've reset the board to make sure it's running at 9600baud. The parity matches up with Arduinos 8-N-1. I know the MP3s loaded on my card play because I can ground any one of pads K1-K8 and the correct audio will play. I'm using Software Serial and have Arduino pin 3 to the RX pin on the module. I am not using the busy pin at this point, here's my code:

#include <SoftwareSerial.h>


SoftwareSerial mp3(4,3); //RX, TX

void setup() {
// initialize the serial communication:
Serial.begin(9600); //Set to 9600 bps
mp3.begin(9600); //Set mp3 serial to 9600 bps
delay(2000);

}

void loop()
{
  mp3.write(0x01); // Play 1st file
  delay(5000);
  
}

All I am trying to do at this point is get the 1st file on the card to play. I'm getting nothing. According to the datasheet, the commands are hex, am I doing this right? Maybe I need to be sending two bytes instead of the one? Those being the index number AND the track number? If so, how do I send both bytes? Any other ideas are welcome, I always get the answer I need here and I really appreciate it.

Thanks.

mp3.print("01\r"); // Play 1st file

try this

Thanks for the reply, but that did not work. Any other suggestions?