FP4: minor updates

v2/devices/FP4.yml

@@ -9,12 +9,12 @@ user_actions:
     description: "Please check that your device is a Fairphone 4 (FP4)."
   confirm_os:
     title: "Confirm OS version"
-    description: "Your device must be running the Fairphone OS version of Android 11 before installing Ubuntu Touch. With a previously installed custom ROM, it won't work!"
-    link: "https://support.fairphone.com/hc/en-us/articles/4405858261777"
+    description: "Your device must be running the Fairphone OS version of Android 11 before installing another operating system. With a previously installed custom ROM, it won't work!"
+    link: "https://support.fairphone.com/hc/en-us/articles/18896094650513-Installing-Fairphone-OS-Manually"
   unlock_phone:
     title: "Unlock the bootloader"
-    description: "Before installing Ubuntu Touch you must unlock the bootloader of your phone manually. Follow the steps in the linked page if you haven't already."
-    link: "https://support.fairphone.com/hc/en-us/articles/10492476238865"
+    description: "Before installing another operating system you must unlock the bootloader of your phone manually. Follow the steps in the linked page if you haven't already."
+    link: "https://support.fairphone.com/hc/en-us/articles/10492476238865-Manage-the-Bootloader"
   bootloader:
     title: "Reboot to Bootloader"
     description: "With the device powered off, press and hold the VOLUME DOWN button and plug the device into your PC via USB. After some seconds you'll see the fastboot mode."
@@ -217,12 +217,28 @@ operating_systems:
           postmarketos:interfaces:
     prerequisites: []
     steps:
+      ### Ensure we always start in bootloader mode
       - actions:
           - adb:reboot:
               to_state: "bootloader"
         fallback:
           - core:user_action:
               action: "bootloader"
+      ### Ensure the bootloader has been unlocked already
+      - actions:
+          - fastboot:wait:
+      - actions:
+          - fastboot:assert_var:
+              variable: "unlocked"
+              value: "yes"
+        fallback:
+          - core:user_action:
+              action: "unlock_phone"
+      ### As this is an A/B device, force all future operations in "a" slot.
+      - actions:
+          - fastboot:set_active:
+              slot: "a"
+      ### Flash partitions
       - actions:
           - postmarketos:download:
           - fastboot:erase: