Garbled Output from Uart0

Hi there,

In a custom developed board based off of MDBT53-1M, I am struggling with the serial communication using UART0 pins. Using the default settings, I have been successful in receiving the output in an MDBT dev kit but I am not able to replicate that on the custom board.

Here are the source code, and config files:

`main.c`

/*
 * Copyright (c) 2016 Intel Corporation
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include <stdio.h>
#include <zephyr/kernel.h>
#include <zephyr/drivers/gpio.h>
#include <zephyr/logging/log.h>

LOG_MODULE_REGISTER(HelloWorld, LOG_LEVEL_INF);
/* 1000 msec = 1 sec */
#define SLEEP_TIME_MS   1000


/*
 * A build error on this line means your board is unsupported.
 * See the sample documentation for information on how to fix this.
 */


int main(void)
{
	int ret;
	bool led_state = true;
	printk("strat of the application \n");
	LOG_INF("strat of the application \n");
	
	while (1) {
	
		led_state = !led_state;
		printk("LED state: %s\n", led_state ? "ON" : "OFF");
		LOG_INF("LED state: %s\n", led_state ? "ON" : "OFF");
		k_msleep(SLEEP_TIME_MS);
	}
	return 0;
}

`prj.conf`

CONFIG_GPIO=y
CONFIG_LOG=y

Not using any overlay file as I am not using any peripherals. I have access to uart0 pins: RX, TX, CTS, RTS through a dedicated pin header. Despite there being print statements in every iteration of the loop, I dont see anything on the serial monitor. The same application, however, gives the desired serial messages on MDBT dev kit. 

Some other relevant details:

- MDBT53 is a device based on nRF5340

- SDK v 3.0.0 and Toolchain v 3.1.1

I have followed a similar forum post where the OP recognized a wrongly cleared configuration statement (`CONFIG_UART_CONSOLE=n`) but I dont have that issue in my generated .config file. 

Kindly advise how to debug the issue. 

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