How to Install Custom Recovery (TWRP) on Samsung Galaxy S21 Ultra SM-G998B

Understanding Custom Recovery

• 💡 A custom recovery like TWRP offers more features than the stock recovery, enabling actions such as installing custom ROMs and using ADB sideload.
• 🔑 The primary goal is to unlock the bootloader to allow for these advanced modifications.

Preparing Your Samsung Galaxy S21 Ultra

• ⚠️ Before proceeding, back up your data and remove your Google account, as unlocking the bootloader will erase all data.
• 📶 Ensure your phone is connected to Wi-Fi, as this is necessary for enabling OEM unlocking.
• ⚙️ Navigate to Settings > About phone > Software information and tap the build number seven times to enable Developer Options.
• ✅ Within Developer Options, enable OEM unlocking; it should appear grayed out if Wi-Fi is connected.

Unlocking the Bootloader

• 🔌 Power off your phone, then press and hold Volume Up + Volume Down simultaneously and connect it to your PC via USB cable.
• ⚠️ When the blue screen appears, press and hold Volume Up to proceed to the bootloader unlock prompt.
• 👍 Confirm the unlock by pressing Volume Up again; the phone will then erase its data.

PC Setup and File Preparation

• 💻 Download and install Samsung USB drivers for your PC. A restart is required for them to take effect.
• 🗜️ Download ODIN (version 3.14.4 or later) and extract it.
• 📂 Download the specific TWRP custom recovery and vbmeta disabler files for your SM-G998B model.
• 📂 Extract the TWRP and vbmeta disabler files to a convenient location.

Flashing TWRP with ODIN

• 🖱️ Open ODIN on your PC and connect your phone (which should be in Download Mode).
• ⚠️ In ODIN, go to Options and disable Auto Reboot.
• 📂 Click the AP button in ODIN and select the TWRP .tar file.
• 💾 Click the User Data button and select the vbmeta disabler file.
• ▶️ Click Start to flash the files. This process is quick.

Booting into Custom Recovery and Finalizing

• 🔄 With the cable still connected, press and hold Power + Volume Down for about 7 seconds until the screen turns off.
• ⬆️ Immediately switch your finger from Volume Down to Volume Up while still holding the Power button.
• 📱 Continue holding until the TWRP recovery screen appears. Release the Power button when the Samsung logo shows, keeping Volume Up pressed.
• 🧹 In TWRP, navigate to Wipe > Format Data, type yes, and approve to wipe the phone.
• 🚀 Reboot the system. Your phone should now boot with the custom recovery installed.