Simply run M31 at the end of an SD print

Marlin/Marlin_main.cpp

         if (card_eof) {
           SERIAL_PROTOCOLLNPGM(MSG_FILE_PRINTED);
           print_job_timer.stop();
-          char time[30];
-          millis_t t = print_job_timer.duration();
-          sprintf_P(time, PSTR("%i " MSG_END_HOUR " %i " MSG_END_MINUTE), int(t / 60 / 60), int(t / 60) % 60);
-          SERIAL_ECHO_START;
-          SERIAL_ECHOLN(time);
-          lcd_setstatus(time, true);
           card.printingHasFinished();
           card.checkautostart(true);
         }

Marlin/cardreader.cpp

 
 void CardReader::printingHasFinished() {
   stepper.synchronize();
+  file.close();
   if (file_subcall_ctr > 0) { // Heading up to a parent file that called current as a procedure.
-    file.close();
     file_subcall_ctr--;
     openFile(proc_filenames[file_subcall_ctr], true, true);
     setIndex(filespos[file_subcall_ctr]);
     startFileprint();
   }
   else {
-    file.close();
     sdprinting = false;
     if (SD_FINISHED_STEPPERRELEASE)
       enqueue_and_echo_commands_P(PSTR(SD_FINISHED_RELEASECOMMAND));
-    thermalManager.autotempShutdown();
+    print_job_timer.stop();
+    enqueue_and_echo_commands_P(PSTR("M31"));
   }
 }