If your Nothing Phone (2) fingerprint scanner has stopped recognizing you, it's a frustrating roadblock. The optical in-display sensor can be finicky, but there are several straightforward fixes you can try before assuming the worst.
Clean Your Screen and Finger
This is the most common culprit. The sensor needs a clear view of your fingerprint through the glass. Any smudge, oil, or moisture on the screen or your finger can block it.
Grab a soft, dry microfiber cloth and wipe the entire screen down, paying extra attention to the lower third where the sensor is located. Make sure your own finger is clean and completely dry, too.
Restart Your Phone
A quick reboot can clear out temporary software glitches that might be confusing the sensor. Just press and hold the power button for a couple seconds, then tap "Restart."
If the phone is completely unresponsive, you can force restart it. Press and hold the power button for about 10 seconds until you feel a vibration and see the Nothing logo appear.
Re-register Your Fingerprint
Sometimes the stored fingerprint data gets corrupted. Deleting the old print and setting it up fresh often solves the problem. Head to Settings > Security & privacy > Device unlock > Fingerprint unlock.
You'll need to enter your PIN or password. Tap on the fingerprint you're having trouble with and select "Delete." Now, tap "Add fingerprint" and follow the prompts carefully.
When it asks you to place your finger, use the same part you normally do to unlock the phone. Roll it slightly to capture the edges, and don't lift it until the phone vibrates and tells you to.
Check Your Screen Protector
Not all screen protectors play nice with in-display fingerprint sensors. If you recently applied a new one, that could be the issue. Thick glass protectors or ones with certain coatings can interfere with the sensor's light.
Try removing the protector temporarily to see if the fingerprint reader starts working again. If it does, you might need to look for a protector marketed as compatible with in-display sensors.
Update Nothing OS
Software bugs can affect sensor performance. Nothing regularly releases updates that include fixes for these kinds of issues. Go to Settings > System > System update and tap "Check for update."
If an update is available, install it. I'd recommend doing this while your phone is charging and connected to Wi-Fi. After the update completes, give the fingerprint sensor another try.
Try a Different Finger or Position
If you injured or cut the finger you registered, the sensor might not recognize it. Try registering a different finger altogether in the security settings.
Also, pay attention to how you're placing your finger. Are you using the very tip, or the flat pad? The sensor needs a good, consistent contact area. Make sure you're pressing firmly enough, but not so hard that you're mashing your finger.
Boot Into Safe Mode
A third-party app could be causing a conflict. Booting into Safe Mode temporarily disables all apps you've installed. Press and hold the power button until the power menu appears.
Then, tap and hold the "Power off" option on your screen. A prompt will ask if you want to reboot to Safe Mode. Tap "OK." If the fingerprint sensor works perfectly in Safe Mode, you know a downloaded app is the problem.
You'll need to restart your phone normally to exit Safe Mode. Then, start uninstalling recent apps one by one to find the culprit.
Clear the System Cache
Corrupted cache files can cause all sorts of weird behavior, including sensor failures. You'll need to use the recovery menu to do this. First, power your phone off completely.
Now, press and hold the Power button and the Volume Up button together. Let go when you see the Nothing logo. Use the volume buttons to navigate to "Wipe cache partition" and press the power button to select it.
Confirm the action, then select "Reboot system now." This won't delete any of your personal data, photos, or apps. It just clears temporary system files.
Check for Sensor Interference
Are you trying to unlock the phone while it's on a wireless charger? The electromagnetic field from Qi charging can sometimes interfere with the sensitive optical sensor. I've seen this happen.
Take the phone off the charger and try the fingerprint again. The same goes for very bright, direct sunlight shining on the sensor area. Try shading the screen with your hand or moving into different lighting.
Review Your Security Settings
There's a setting that requires stronger security after a restart. Go to Settings > Security & privacy > Device unlock. Look for an option like "Require PIN for startup" or "Unlock using fingerprint after restart."
If this is on, you'll always need your PIN the first time you unlock the phone after rebooting. This is a security feature, not a bug. After that first unlock, the fingerprint should work normally.