Fix calibration button

There was an issue with the calibration button on _some_ flight controllers; after performing a fresh installation of INAV. This issue did not appear on my test F405-WING. I have moved the check to the FC object, and added extra checks for the default accelerometer values. Works as expected on my test FC.

js/fc.js

@@ -763,6 +763,24 @@ var FC = {
 
         return retVal;
     },
+    getAccelerometerCalibrated: function () {
+        var calibrated = true;
+        var flagNames = FC.getArmingFlags();
+
+        if (CALIBRATION_DATA.accGain.X === 4096 && CALIBRATION_DATA.accGain.Y === 4096 && CALIBRATION_DATA.accGain.Z === 4096 && 
+            CALIBRATION_DATA.accZero.X === 0 && CALIBRATION_DATA.accZero.Y === 0 && CALIBRATION_DATA.accZero.Z === 0
+           ) {
+            calibrated = false;
+        }
+
+        if ((calibrated) && flagNames.hasOwnProperty(13)) {
+            if (bit_check(CONFIG.armingFlags, 13)) {
+                calibrated = false;
+            }
+        }
+
+        return calibrated;
+    },
     getUserControlMode: function () {
         return [
             "Attitude",

tabs/calibration.js

@@ -176,24 +176,16 @@ TABS.calibration.initialize = function (callback) {
     }
 
     function setupCalibrationButton(callback) {
-        let showCalibrate = false;
-        var flagNames = FC.getArmingFlags();
-        if (flagNames.hasOwnProperty(13)) {
-            if (bit_check(CONFIG.armingFlags, 13)) {
-                showCalibrate = true;
-            }
-        }
-    
-        if (showCalibrate) {
-            $('#calibrate-start-button').html(chrome.i18n.getMessage("AccBtn"));
-            $('#calibrate-start-button').prop("title", chrome.i18n.getMessage("AccBtn"));
-            $('#calibrate-start-button').addClass("calibrate");
-            $('#calibrate-start-button').removeClass("resetCalibration");
-        } else {
+        if (FC.getAccelerometerCalibrated()) {
             $('#calibrate-start-button').html(chrome.i18n.getMessage("AccResetBtn"));
             $('#calibrate-start-button').prop("title", chrome.i18n.getMessage("AccResetBtn"));
             $('#calibrate-start-button').removeClass("calibrate");
             $('#calibrate-start-button').addClass("resetCalibration");
+        } else {
+            $('#calibrate-start-button').html(chrome.i18n.getMessage("AccBtn"));
+            $('#calibrate-start-button').prop("title", chrome.i18n.getMessage("AccBtn"));
+            $('#calibrate-start-button').addClass("calibrate");
+            $('#calibrate-start-button').removeClass("resetCalibration");
         }
     
         if (callback) callback();