How to Manually Update Samsung Galaxy A21s using Odin (Keep Your Data)

Preparing for the Manual Update

• 💡 This video demonstrates how to manually update your Samsung Galaxy A21s using Odin on a computer, a method useful when OTA updates fail or the bootloader is unlocked.
• ✅ Before starting, it's recommended to set up your phone and establish a screen lock to verify that your data is preserved during the process.

Verifying Phone Model and Revision

• 🔍 To ensure you download the correct firmware, check your phone's model number (e.g., SM-A217F for international, SM-A217M for US) and software revision (e.g., XXSC, where 'C' indicates the revision level).
• ⚠️ It's crucial to know your revision because you cannot downgrade to older revisions; you can only install the current or a newer one.
• 📌 For those unable to check in settings, the model number can often be found on the phone's original box.

Entering Download Mode and Finding Firmware

• 📲 To enter Download Mode, power off the phone, then press and hold Volume Up and Volume Down simultaneously while plugging in the USB cable connected to your computer.
• 🚀 A short press of Volume Up will confirm entry into Download Mode, where you can also see the revision code (e.g., B12, C12, indicating the 12th revision).
• 💻 Search for your phone's model number followed by "firmware" on a reliable website to find and download the correct firmware package.

Downloading Necessary Tools and Files

• 🛠️ You will need to download Samsung USB drivers and the latest version of Odin from their respective official websites.
• 📂 After downloading, extract all files (Odin, drivers, and firmware) to easily access them.
• 💻 Install the Samsung USB drivers and restart your computer to ensure they are properly recognized.

Loading Firmware into Odin and Flashing

• 🔌 Connect your phone (already in Download Mode) to the computer. A successful connection will show a COM port in Odin.
• 🎯 Load the firmware files into Odin: BL (Bootloader), AP (Android Partition), CP (Core Partition), and HOME_CSC.
• ⚠️ Crucially, use HOME_CSC instead of CSC to avoid wiping your phone's data. Standard CSC will erase all data.
• ▶️ Click "Start" in Odin and wait for the process to complete (approximately 7 minutes), after which the phone will automatically restart.
• ✅ Upon restart, verify that your phone is on and all your data remains intact, confirming a successful data-preserving update.