1: Download and Install Samsung USB Driver on your computer. If Samsung USB Driver is already installed on your computer, then Skip this Step.
2: Download and extract the Galaxy S9 Plus SM-G965F U9 Firmware files on your computer.
3: Now, Switch off your Smartphone.
4: After switching off the phone, you need to boot into Download Mode. To boot into download mode.
Press and hold Volume Down, Home and Power button at the same time for 5-8 seconds until download mode is active.
5: In the Download mode, you will be able to see a Warning Yellow Triangle Sign. In this situation, you have to press the Volume Up key to continue.
6: Now, Download and open Odin. Then connect your Smartphone to the computer.
7: Once you have connected the Smartphone to the computer, Odin will automatically recognize the device and show the “Added” message at the lower-left panel.
8: Once Odin detects your device, click on the PDA button, and select the Firmware.tar file.
9: Now, click on the Start button in Odin to begin the Flashing.
10: Flashing usually takes 30-50 seconds to complete the process on your Phone.
The once Firmware process is completed you will be able to see a Green Box with Pass written on it in Odin. During this process, the Smartphone will reboot automatically.
Once you see, the Pass message in Odin, you can disconnect your Device from the computer.
The flashing process will begin and should take about 10–12 minutes. It may take some time for your device to reboot, but don’t be alarmed.
When your Galaxy S9 Plus SM-G965F U9 finally boots up, you should now be running your desired firmware.
If you want to check that the correct firmware is installed, head to Settings –> About Phone –> Software Information. The firmware number is located under the “Baseband version.”