Boolean stuck on true, toilet occupancy(help)

In the part of your code that says ....

else if (buttonState == HIGH){if (check == true){;}
else if (sense == HIGH){check = true;}}

That kind of means .... if 'check' is 'true', then do nothing..... right?

Or did you mean to write 'check = true' .... instead of 'if(check == true)' ?

Should probably code things like this.......

if (buttonState== LOW) {
   check = false;
}
else if (buttonState == HIGH) {
          if (check == true){
          }                                                       //do nothing
          else if (sense == HIGH) {
                 check = true;
                }
       }