Ensure the OnePlus Nord 2T is completely powered off. Press and hold the power button until the power menu appears, then select 'Power Off'. Wait until the device is fully shut down.

Using a SIM eject tool or a paperclip, eject the SIM card tray from the phone. Set the tray and SIM card aside in a safe place.

Use a heat gun or hairdryer to gently warm the edges of the back cover. This will soften the adhesive, making it easier to remove. Be careful not to overheat the device.

Place a suction cup on the back cover and gently pull to create a small gap. Insert a plastic opening tool into the gap and carefully work your way around the perimeter to release the adhesive. Avoid using metal tools to prevent damaging the back cover.

With the back cover removed, locate the battery connector. Use a spudger to gently pry up and disconnect the battery connector from the motherboard.

Use a plastic tool to gently lift the battery out of its compartment. If necessary, use tweezers to carefully peel off any adhesive strips holding the battery in place. Avoid bending or puncturing the battery.

Place the new battery into the compartment, ensuring it is properly aligned. Connect the battery connector to the motherboard. Secure the battery using new adhesive strips or double-sided tape.

Align the back cover with the device and press down firmly around the edges to secure the adhesive. If necessary, apply gentle heat again to ensure a strong seal.

Insert the SIM card back into the tray and slide the tray back into the phone.

Power on the device by holding the power button. Check to ensure the phone powers on and the battery is functioning correctly.