XBee3 and random data in serial

Hey everyone. I seem to be having an issue with a project I am working on and I could really use a bit of guidance. The hardware is a custom board with an ATMega328P chip and an XBee3 micro module (I can provide schematics if needed). All of my other code works fine but the XBee isn’t transmitting (or at least the other XBee connected to my PC isn’t receiving). When I upload the following code to the board to check if it can receive data, I get a repeating output in the serial monitor.

Code running on the custom board:

/// XBEE VARS
#include <SoftwareSerial.h>
#define XBEE_RX_PIN 12
#define XBEE_TX_PIN 13
SoftwareSerial xbee(XBEE_RX_PIN, XBEE_TX_PIN);
String outbound = "";


void setup()
{
  pinMode(XBEE_RX_PIN, INPUT);
  pinMode(XBEE_TX_PIN, OUTPUT);
  Serial.begin(9600);
  xbee.begin(9600);
}


void loop()
{
  if (xbee.available()) {
    byte temp = xbee.read();
    Serial.println(temp);
  }
  delay(1000);
}

Serial output from the board that repeats:

126
0
2
138
13
104

I have checked the pins and solders for continuity and everything seems fine. One thing to note is that when I initially bootloaded and uploaded the code to the board with an AVR Pocket Programmer, I did not disable the 5v supply. I believe the XBee is only designed for 3.3v. Am I looking at a possibly fried XBee module or is this something else entirely?

Thanks!