#relaunch-and-powerwash and #relaunch buttons are mutually exclusive.

chrome/browser/resources/help/help.js

Index: chrome/browser/resources/help/help.js
diff --git a/chrome/browser/resources/help/help.js b/chrome/browser/resources/help/help.js
index d28094dee2a9898b045e03bff3376a0b1951683f..547b8054e44b30b5a974e57eceffabc66c4df86f 100644
--- a/chrome/browser/resources/help/help.js
+++ b/chrome/browser/resources/help/help.js
@@ -279,22 +279,27 @@ cr.define('help', function() {
         $('update-status-message').innerHTML = message;
       }
 
+      // Following invariant must be established at the end of this function:
+      // { ~$('relaunch_and_powerwash').hidden -> $('relaunch').hidden }
+      var relaunchAndPowerwashHidden = true;
+      if ($('relaunch-and-powerwash')) {
+        // It's allowed to do powerwash only for customer devices,
+        // when user explicitly decides to update to a more stable
+        // channel.
+        relaunchAndPowerwashHidden =
+            !this.powerwashAfterUpdate_ || status != 'nearly_updated';
+        $('relaunch-and-powerwash').hidden = relaunchAndPowerwashHidden;
+      }
+
       var container = $('update-status-container');
       if (container) {
         container.hidden = status == 'disabled';
-        $('relaunch').hidden = status != 'nearly_updated';
+        $('relaunch').hidden =
+            (status != 'nearly_updated') || !relaunchAndPowerwashHidden;
 
         if (!cr.isMac)
           $('update-percentage').hidden = status != 'updating';
       }
-
-      if ($('relaunch-and-powerwash')) {
-        // It's allowed to do powerwash only for customer devices,
-        // when user explicitly decides to update to a more stable
-        // channel.
-        $('relaunch-and-powerwash').hidden =
-            !this.powerwashAfterUpdate_ || status != 'nearly_updated';
-      }
     },
 
     /**