fix: logic error in build+flash function

scripts/install_klipper.sh

@@ -254,10 +254,12 @@ flash_routine(){
     case "$yn" in
       Y|y|Yes|yes|"")
         echo -e "###### > Yes"
+        FLASH_FIRMWARE="true"
         get_mcu_id
         break;;
       N|n|No|no)
         echo -e "###### > No"
+        FLASH_FIRMWARE="false"
         break;;
       *)
         print_unkown_cmd

scripts/ui/advanced_menu.sh

@@ -40,10 +40,12 @@ advanced_menu(){
         clear
         print_header
         flash_routine
+        if [ $FLASH_FIRMWARE = "true" ]; then
           ### build in a sleep to give the user a chance to have a look at the
           ### MCU IDs before directly starting to build the klipper firmware
           status_msg "Please wait..." && sleep 10 && build_fw
           flash_mcu
+        fi
         print_msg && clear_msg
         advanced_ui;;
       5)