If your Nothing Phone (3) fingerprint scanner suddenly stops recognizing you, it can lock you out of your phone and apps. This is usually a software hiccup or a simple fix, not a broken sensor. Let's get it working again.
Restart Your Phone
I'd start with this one. A quick restart clears out any temporary glitches that might be messing with the sensor. Just press and hold the Volume Down and Power buttons together for about 10 seconds until you see the Nothing logo. It takes about 30 seconds total and often solves the problem right away.
Clean the Screen and Your Finger
The optical fingerprint sensor under the screen needs a clear view. Any smudges, grease, or moisture on the screen or your finger can block the scan. Give the lower part of your screen a good wipe with a soft, dry microfiber cloth.
Make sure your finger is clean and dry, too. Hand sanitizer, lotion, or sweat can create a barrier. If your hands are often damp, try registering a fingerprint when they're completely dry for better reliability.
Re-register Your Fingerprint
Sometimes the stored fingerprint data gets corrupted. Removing it and adding it back is a very reliable fix. Open Settings > Security & privacy > Device unlock > Fingerprint.
Enter your PIN, then tap the fingerprint you're having trouble with. Hit Delete. Now, tap Add fingerprint and follow the prompts. Press firmly and roll your finger slightly to capture the edges, just like it shows on screen.
Check for a Software Update
Nothing regularly releases updates for Nothing OS that include bug fixes and performance improvements. An outdated system could be the culprit. Go to Settings > System > System update and tap Check for update.
If an update is available, install it. It's a good idea to plug your phone in or make sure you have plenty of battery first. After the update completes, test your fingerprint scanner again.
Inspect Your Screen Protector
This is a common issue. A thick, low-quality, or poorly aligned screen protector can interfere with the optical sensor's light. If you recently applied a new protector and the scanner stopped working, that's likely the cause.
Try temporarily removing the protector to see if the fingerprint reader works perfectly without it. If it does, you'll need a screen protector specifically marketed as compatible with in-display fingerprint sensors. Some brands even include a "Fingerprint Mode" in the installation guide.
Try a Different Finger or Position
Maybe the finger you registered has a small cut or dry skin that's changed its print slightly. Try unlocking with a different finger you've also registered. If that works, you know the sensor itself is fine.
Also, pay attention to how you place your finger. Are you hitting the same spot? Try to cover the entire sensor area shown on the screen and don't lift your finger too quickly. A little firm pressure helps.
Boot Into Safe Mode
This checks if a third-party app you installed is causing a conflict. To boot Safe Mode, press and hold the power button until the power menu appears. Then, tap and hold the Power off option until you see a prompt to reboot to Safe Mode. Tap it.
If the fingerprint scanner works perfectly in Safe Mode, a recently downloaded app is likely to blame. You'll need to uninstall apps one by one (starting with the most recent) to find the offender.
Clear the System Cache
Corrupted temporary system files can cause all sorts of weird behavior, including sensor failures. You'll need to use the recovery menu. First, power your phone off completely.
Now, press and hold the Power and Volume Up buttons together. When you feel a vibration, release the Power button but keep holding Volume Up until you see the recovery menu. Use the volume buttons to navigate to Wipe cache partition and press the power button to select it. Confirm, then select Reboot system now.
Check Your Security Settings
There are a couple of settings that can affect the scanner. First, go to Settings > Security & privacy > Device unlock and make sure Fingerprint is toggled on. Also, check if you have any "Smart Lock" features enabled that might be overriding the need for a fingerprint in certain situations, confusing the system.
Another setting to look at is "Increase touch sensitivity," which is sometimes added for use with screen protectors. You can find this in Settings > Display. Toggling this on can sometimes improve scanner performance with a protector installed.
Reset All App Preferences
This is a less invasive step before a full reset. It resets permissions, background restrictions, and default app assignments without deleting your personal data. Go to Settings > System > Reset options > Reset app preferences.
Tap Reset apps. After your phone reboots, you'll need to re-grant permissions to apps as you use them, but it can clear up conflicts that are hampering system functions like the fingerprint reader.