Add Blank BG screen to E3V2 for S1 screen compat

Marlin/src/lcd/e3v2/creality/dwin_lcd.cpp

@@ -49,6 +49,7 @@ void DWIN_Startup() {
   #if DISABLED(SHOW_BOOTSCREEN)
     DWIN_Frame_Clear(Color_Bg_Black); // MarlinUI handles the bootscreen so just clear here
   #endif
+  DWIN_JPG_ShowAndCache(3);
   DWIN_UpdateLCD();
 }
 

Marlin/src/lcd/e3v2/enhanced/dwin.cpp

@@ -1834,6 +1834,7 @@ void DWIN_Startup() {
   DWINUI::onCursorErase = Erase_Menu_Cursor;
   DWINUI::onTitleDraw = Draw_Title;
   DWINUI::onMenuDraw = Draw_Menu;
+  DWIN_JPG_ShowAndCache(3);
   HMI_SetLanguage();
 }
 
@@ -1934,6 +1935,7 @@ void DWIN_RebootScreen() {
   DWINUI::Draw_CenteredString(Color_White, 220, GET_TEXT_F(MSG_PLEASE_WAIT_REBOOT));
   DWIN_UpdateLCD();
   delay(500);
+  DWIN_JPG_ShowAndCache(3)
 }
 
 void DWIN_Redraw_screen() {
@@ -3339,7 +3341,7 @@ void Draw_Control_Menu() {
     #if ENABLED(CASE_LIGHT_MENU)
       #if ENABLED(CASELIGHT_USES_BRIGHTNESS)
         MENU_ITEM(ICON_CaseLight, GET_TEXT_F(MSG_CASE_LIGHT), onDrawSubMenu, Draw_CaseLight_Menu);
-      #else 
+      #else
         MENU_ITEM(ICON_CaseLight, GET_TEXT_F(MSG_CASE_LIGHT), onDrawCaseLight, SetCaseLight);
       #endif
     #endif
@@ -3601,7 +3603,7 @@ void Draw_Tune_Menu() {
       MENU_ITEM(ICON_CaseLight, GET_TEXT_F(MSG_CASE_LIGHT), onDrawCaseLight, SetCaseLight);
     #elif ENABLED(LED_CONTROL_MENU) && DISABLED(CASE_LIGHT_USE_NEOPIXEL)
       MENU_ITEM(ICON_LedControl, GET_TEXT_F(MSG_LEDS), onDrawLedStatus, SetLedStatus);
-    #endif    
+    #endif
     EDIT_ITEM(ICON_Speed, GET_TEXT_F(MSG_SPEED), onDrawSpeedItem, SetSpeed, &feedrate_percentage);
     #if HAS_HOTEND
       HotendTargetItem = EDIT_ITEM(ICON_HotendTemp, GET_TEXT_F(MSG_UBL_SET_TEMP_HOTEND), onDrawHotendTemp, SetHotendTemp, &thermalManager.temp_hotend[0].target);

Marlin/src/lcd/e3v2/jyersui/dwin.cpp

@@ -5454,6 +5454,8 @@ void MarlinUI::init_lcd() {
     DWIN_UpdateLCD();
     delay(20);
   }
+
+  DWIN_JPG_ShowAndCache(3);
   DWIN_JPG_CacheTo1(Language_English);
   CrealityDWIN.Redraw_Screen();
 }

Marlin/src/lcd/e3v2/marlinui/dwin_lcd.cpp

@@ -45,6 +45,7 @@ void DWIN_Startup() {
   const bool success = DWIN_Handshake();
   if (success) DEBUG_ECHOLNPGM("ok."); else DEBUG_ECHOLNPGM("error.");
   DWIN_Frame_SetDir(TERN(DWIN_MARLINUI_LANDSCAPE, 0, 1));
+  DWIN_JPG_ShowAndCache(3);
   DWIN_Frame_Clear(Color_Bg_Black); // MarlinUI handles the bootscreen so just clear here
   DWIN_UpdateLCD();
 }