EPS8266 Wemos D1 Mini - automatic reboot

Question

I've made a simple sketch which displays my subscriber count and it is working fully. I have made a wooden box for it so I am going to screw it together with the Wemos inside. When I disconnect the usb chord and stick it back in the Sketch seems to reboot but nothing is displayed on the Dot Matrix. If I push the reset button however, it reboots fully and the Matrix displays the numbers again.

When I run the Arduino serial monitor and unplug and plug it back in, it runs the sketch but nothing show on the Matrix. It's doing my head in.

I'm not sure if the code would help but I can of course publish that if needed.

The question: Is there any way to code a full reboot upon reconnection to power? Since it's going to be stuck in a wooden box it would be really nice if it would reboot when the power is turned back on so I don't have to open the box and push reset every time.

Any help is appreciated. Thanks!

The code:

// Libraries included

#include <MD_Parola.h>
#include <MD_MAX72xx.h>
#include <SPI.h>
#include "Arduino.h"
#include <ESP8266WiFi.h>
#include <WiFiClientSecure.h>
#include "JsonStreamingParser.h"
#include <ArduinoJson.h>

#include "InstagramStats.h"
#include <YoutubeApi.h>

#include "theSwedishMaker.h"


const uint16_t WAIT_TIME = 6000; //Time between fecthing data.


// Define the typ of hardware and the pins used. 

#define HARDWARE_TYPE MD_MAX72XX::FC16_HW
#define MAX_DEVICES 4

#define CLK_PIN   12
#define DATA_PIN  15
#define CS_PIN    13

// Hardware SPI connection
//MD_Parola P = MD_Parola(HARDWARE_TYPE, CS_PIN, MAX_DEVICES);
// Arbitrary output pins
MD_Parola P = MD_Parola(HARDWARE_TYPE, DATA_PIN, CLK_PIN, CS_PIN, MAX_DEVICES);



#define API_KEY "********" //Your Youtube API-Key 
#define CHANNEL_ID "Youtube Channel ID" // Your youtube channel ID. 

String userName = "TheSwedishMaker"; // Your Instagram Username


WiFiClientSecure client; //For ESP8266 boards
InstagramStats instaStats(client);

YoutubeApi api(API_KEY, client);

// =======================================================================
// Configuration of router settings
// =======================================================================

const char* ssid     = "NETWORKNAME";      // SSID of local network
const char* password = "*******";                // Password on network

void setup() 
{
  P.begin();
  P.setFont(fontSubs);

  // Connecting to wifi
  Serial.begin(115200);
  Serial.print("Connecting WiFi ");
  WiFi.begin(ssid, password);
  P.print(" WiFi...");
  while (WiFi.status() != WL_CONNECTED) {
    Serial.print("."); delay(500);
  }
  Serial.println("");
  Serial.print("Connected: "); Serial.println(WiFi.localIP());

  client.setInsecure();
}


void loop(void)
{

  Serial.println("Getting data ...");
  P.print("fetching");
  int cnt = 0;
  //int yt1;
  long yt1,yt2,insta;
    while(1) {
    if(!cnt--) {
     cnt = 50;
     if(api.getChannelStatistics(CHANNEL_ID))
      yt1 = api.channelStats.subscriberCount; 
      yt2 = api.channelStats.viewCount;
      InstagramUserStats response = instaStats.getUserStats(userName);
      insta = response.followedByCount;    
    }

    // FORMATO
       String subsCount = num_format(yt1);
       String viewCount = num_format(yt2);
       String instaFollowers = num_format(insta);

    // PRINT
    Serial.println(subsCount);
    P.print("*" + subsCount); 
    delay(3500);
   // P.print("*" + viewCount); //Uncomment if your want to show viewcount.
   // delay(3500); //Uncomment if you want to show viewcount.
    P.print("&" + instaFollowers); 
    delay(5000);
    }}


String num_format(long num){
     String num_s;
     long num_original = num;
     if (num>99999 && num<=999999){
        num = num / 1000;
        long fraction = num_original%1000;
        String num_fraction = String(fraction);
        String decimal = num_fraction.substring(0,1);
        num_s = String(num) + "." + decimal + "K";          
    }
    else if(num>999999){
        num = num / 1000000;
        long fraction = num_original%1000000;
        String num_fraction = String(fraction);
        String decimal = num_fraction.substring(0,1);
        if (num_original<100000000){
          num_s = " " + String(num) + "." + decimal + "M";      
        }
        else{
        num_s = String(num) + "." + decimal + "M";
        }
    }
    else{
        int num_l = String(num).length();
        char num_f[15];
        int blankDigits = 6 - num_l;
        for(int i = 0; i < blankDigits; i++){
          num_f[i] = ' '; 
        }
        num_f[blankDigits] = '\0';
        num_s = num_f + String(num);
    }
    return num_s;
}