Face ID and fingerprint sensors fail more often than most people expect. Many assume the repair caused the problem.
However, the truth is different. These sensors are very sensitive and tightly linked to the phone’s mainboard.

Also, sensors can already be weak due to drops, heat, or frame pressure. The phone may still unlock, but the flex cable or chipset might be damaged.
As a result, the sensor stops working the moment the device is opened for repair.

When Face ID and Fingerprint Usually Survive a Repair

In most cases, biometrics survive without any issues. This happens when the sensor area has no cracks, dents, or crushed corners.
We always check the sensor before starting the repair.

However, if the sensor zone is already damaged, failure can happen at any moment. It may still work at drop-off, but the weakened cable can break as soon as
the display is removed. This is because broken glass and frame pressure damage the sensor over time.

Typical Patterns When Biometrics Fail After a Repair

We often see similar failure patterns. These cases help explain why the sensor stops working after a repair.

• iPhones with cracked TrueDepth flex cables unlock until the screen is lifted. After that, Face ID becomes unavailable.
• Samsung and Xiaomi optical sensors lose accuracy when the frame is bent or twisted.
• Ultrasonic sensors fail when long-term pressure affects the glass or sensor alignment.
• Edge impacts shift the screen slightly, which misaligns the reading point under the display.

These failures do not start during the repair. Instead, the repair exposes damage that was already there.

Apple Face ID vs Android Fingerprint: What Can Be Fixed?

Apple devices are very strict. The Face ID parts are paired to the Secure Enclave on the mainboard. Because of this, even a small flex cable tear
can permanently disable Face ID. A simple part swap cannot fix it.

On the other hand, some Android models allow simple fingerprint module replacement. However, many models use an in-display sensor that is fused
to the screen. As a result, a full display replacement may be required. We explain this clearly to customers before proceeding.

Why Face ID or Fingerprint Can Stop Working After a Repair

There are several common reasons why biometrics fail after a repair. These include:

• A cracked or weakened sensor flex cable.
• Internal chipset damage from impact or heat.
• Broken glass applying long-term pressure on the sensor.
• A bent frame that shifts the alignment of the sensor.
• Security pairing that prevents part replacement.
• In-display sensor failure from moisture or pressure.

Because of these risks, we always inform customers before starting high-risk work.
If the sensor area is heavily damaged, failure may occur even if the feature works during check-in.

Our goal is to give customers clear expectations. We want you to understand what is possible and what may not be reversible.
Also, understanding how biometrics work helps prevent confusion.

The key point is simple: repairs do not break biometric sensors. Previous impact damage does. The repair just reveals it.

Disclaimer

This article is for general information and reference only. Device conditions vary, and you should not rely solely on this content
to make repair or safety decisions. For accurate diagnosis or repair, please have your device inspected by a qualified technician.