diff --git a/src/logic/flasher.rs b/src/logic/flasher.rs
index 7a197ea..606902c 100644
--- a/src/logic/flasher.rs
+++ b/src/logic/flasher.rs
@@ -648,9 +648,29 @@ pub fn flash_firmware(
     // We pass reboot=false here so the chip stays in bootloader mode for   //
     // the MD5 verification step that follows.  A hard reset is done after. //
     // ------------------------------------------------------------------ //
-    send_progress(0.93, "Finalizing write...".into());
+    send_progress(0.92, "Finalizing write...".into());
     flash_end(&mut port, false)?;
 
+    // ------------------------------------------------------------------ //
+    // Step 8b: Erase otadata partition (0xF000, 8KB) when flashing factory //
+    //                                                                       //
+    // If we just wrote to the factory partition, the bootloader might       //
+    // still have otadata pointing to ota_0. We erase otadata to force      //
+    // the bootloader to fall back to factory on next boot.                 //
+    // ------------------------------------------------------------------ //
+    if offset == 0x20000 {
+        send_progress(0.93, "Erasing otadata (force factory boot)...".into());
+        const OTADATA_OFFSET: u32 = 0xF000;
+        const OTADATA_SIZE: u32 = 0x2000; // 8 KB
+        flash_begin(&mut port, OTADATA_OFFSET, OTADATA_SIZE, FLASH_BLOCK_SIZE)?;
+        let empty_block = vec![0xFFu8; FLASH_BLOCK_SIZE as usize];
+        let otadata_blocks = (OTADATA_SIZE + FLASH_BLOCK_SIZE - 1) / FLASH_BLOCK_SIZE;
+        for i in 0..otadata_blocks {
+            flash_data(&mut port, i, &empty_block)?;
+        }
+        flash_end(&mut port, false)?;
+    }
+
     // ------------------------------------------------------------------ //
     // Step 9: MD5 post-write verification                                  //
     //                                                                       //