if(digitalRead(BTN)==HIGH){
    delay(700);                    // 300ms 이상 눌렀다면
    if(count<8){ mode=1; flag=0; } // 800ms 이하
    else{                          // 800ms 이상 초기모드
      mode=0; flag=0;              // 아무 것도 하지 않고
      while(!digitalRead(BTN));    // 버튼 입력을 기다림
    }
  }
 
count를 증가하는 곳이 없습니다.
//
 
// MCU BASIC: https://www.basic4mcu.com
// DateTime : 2019-01-24 오전 10:30:10
// by Ok-Hyun Park
//
//버튼을 길게 800ms 이상 누르면 초기 상태로 돌아가려고 하는데.동작을 하지 않습니다.
//
#define U16 unsigned int
int   R=6,G=9,B=10,BTN=2,pump=7;
//
int   reading,mode=0,val=0,count=0,flag=0;
long  lastChangeTime=0,shortPressTime=600,longPressTime=1000;
float voltage=0;
//
int flag=0;
//
void setup(){
  pinMode(BTN,INPUT);
  pinMode(charge,INPUT_PULLUP);
  pinMode(pump,OUTPUT);
  pinMode(R,OUTPUT);
  pinMode(G,OUTPUT);
  pinMode(B,OUTPUT);
}
//
void setColor(U16 r1,U16 g1,U16 b1,U16 rate){
  float f=rate/255.0;
  r1*=f; g1*=f; b1*=f;
  analogWrite(R,r1); analogWrite(G,g1); analogWrite(B,b1);
}
//
void loop(){
  val=analogRead(0);
  voltage=(float)val*5/1024.0;
  //--------------------------------------------
  if(digitalRead(BTN)==HIGH){
    if(flag==0){ flag=1; count=0; }
    count++;
  }
  else{
    if(flag){ flag=0; 
      if(count<8){ mode=1; flag=0; } // 800ms 이하
      else       { mode=0; flag=0; } // 800ms 이상
    }
  }
  //
  delay(100);
  //--------------------------------------------
  if(mode==1){
    val=analogRead(0);
    voltage=(float)val*5/1024.0;
    if(voltage>=1.7){ // 밧데리 전압이 3.5V이하는 제한...A0에 들어오는 실제전압값이 설정값 1.72면 같다고 인식해서 충전필요상태로 표시
      if(flag==0){ flag=1;
        digitalWrite(pump,HIGH);
        for(int k=0; k<60; k++){
          for(int i=0; i<=255; i++){ setColor(255,0,127,i); delayMicroseconds(3800); }
          for(int i=255; i>=0; i--){ setColor(255,0,127,i); delayMicroseconds(3800); }
        }
        digitalWrite(pump,LOW);
        for(int k=0; k<457*8; k++){
          for(int i=0; i<=255; i++){ delayMicroseconds(3800); }
          for(int i=255; i>=0; i--){ delayMicroseconds(3800); }
        }
        digitalWrite(pump,HIGH);
        for(int k=0; k<30; k++){
          for(int i=0; i<=255; i++){ setColor(255,0,127,i); delayMicroseconds(3800); }
          for(int i=255; i>=0; i--){ setColor(255,0,127,i); delayMicroseconds(3800); }
        }
        digitalWrite(pump,LOW);
      }
    }
    else{
      if(flag==0){ flag=1;
        digitalWrite(pump,LOW);
        for(int k=0; k<3; k++){
          for(int i=0; i<=255; i++){ setColor(255,0,0,i); delayMicroseconds(3800); }
          for(int i=255; i>=0; i--){ setColor(255,0,0,i); delayMicroseconds(3800); }
        }
      }
    }
  }
}