How to Flash Stock ROM on Samsung Galaxy S21 Ultra 5G Using Odin

Preparing to Flash Stock ROM

• 💡 Before flashing, verify your device model (e.g., G998B) and software revision (e.g., D) in the phone's settings.
• ⚠️ It's crucial to understand that you can only flash firmware with a revision number equal to or newer than your current one.
• 📌 Checking the service provider software version (CSC code) is also important for selecting the correct firmware.

Downloading Firmware and Tools

• 💻 Search for your specific model number followed by "firmware" to find compatible ROMs on websites like hardreset.info.
• ⚙️ Download the Samsung USB drivers and the latest version of Odin (e.g., 3.14.4) from a reliable source.
• 💾 Ensure you download the correct firmware version, paying attention to the revision and CSC codes, as firmware files can be very large (around 9 GB).

Installing Drivers and Odin

• 🔌 Install the downloaded Samsung USB drivers and restart your computer for the changes to take effect.
• 📂 Extract both the Samsung USB drivers and Odin files after downloading them.

Flashing the Stock ROM with Odin

• 📱 Connect your phone to the computer and boot it into Download Mode by holding Volume Up and Volume Down while plugging in the USB cable.
• 🖱️ Open Odin and load the firmware files: BL, AP, CP, and CSC. Choose the standard CSC option if you want to wipe data, or Home CSC to attempt to keep your data (use with caution).
• ▶️ Once the phone is recognized by Odin and files are loaded, click Start to begin the flashing process.
• ⚠️ If you encounter connection issues, try using a different USB cable or port. A broken port on the phone can cause failures.
• ✅ Upon successful flashing, the device will restart. This process can take some time.