Application timer in Secure bootloader.

Question

Dear team, Device - nRF52832 SDK - nRF_SDK_15.0.0 Softdevice - s132_nrf_6.0.0 IDE - Segger embedded studio 
 My application needs to toggle one gpio pin using app timer in secure bootloader code. I tried to create app timer in bootloader code but advertisement stops. I can't understand the reason behind that. 
 Here is my main function as below. 
 static void Min1_lowpower_event_timeout_handler(void * p_context) {
 ret_code_t err_code;
 UNUSED_PARAMETER(p_context);
 nrf_gpio_cfg_output(4);
 nrf_gpio_pin_set(4);
 nrf_delay_us(10)
 nrf_gpio_pin_clear(4);
 //Min1CompletionCheck = true;
}

/**@brief Function for application main entry. */
int main(void) {
 uint32_t ret_val;
 ret_code_t err_code;

 // Protect MBR and bootloader code from being overwritten.
 APP_SCHED_INIT(SCHED_MAX_EVENT_DATA_SIZE, SCHED_QUEUE_SIZE);

 //timers_init();

 err_code = app_timer_init();
 APP_ERROR_CHECK(err_code);
 err_code = app_timer_create( & m_1min_lowpower_event_timer_id, APP_TIMER_MODE_REPEATED, Min1_lowpower_event_timeout_handler);
 APP_ERROR_CHECK(err_code);
 err_code = app_timer_start(m_1min_lowpower_event_timer_id, INTERVAL_1SEC, NULL);
 APP_ERROR_CHECK(err_code);
 ret_val = nrf_bootloader_flash_protect(0, MBR_SIZE, false);
 APP_ERROR_CHECK(ret_val);
 ret_val = nrf_bootloader_flash_protect(BOOTLOADER_START_ADDR, BOOTLOADER_SIZE, false);
 APP_ERROR_CHECK(ret_val);

 (void) NRF_LOG_INIT(app_timer_cnt_get);
 NRF_LOG_DEFAULT_BACKENDS_INIT();

 NRF_LOG_INFO("Inside main");*/

 ret_val = nrf_bootloader_init(dfu_observer);
 APP_ERROR_CHECK(ret_val);

 //err_code = app_timer_start(m_battery_timer_id, APP_TIMER_TICKS(1000), NULL);
 //APP_ERROR_CHECK(err_code);
 // Either there was no DFU functionality enabled in this project or the DFU module detected
 // no ongoing DFU operation and found a valid main application.
 // Boot the main application.
 nrf_bootloader_app_start();

 // Should never be reached.
 NRF_LOG_INFO("After main");*/
} 
 Please give me some possible solutions on that.