Vendors describe pairing as a security and calibration measure: a serialised component can be verified as genuine and its calibration data matched to the device. In practice the same mechanism prevents independent repair using identical parts.
What users see
Symptoms range from persistent warning notices to disabled biometrics, reduced display features or non-functional batteries after a swap. Because the part is genuine, diagnostics rarely explain the cause clearly.
Where the rules are heading
Recent repair statutes require parts, tools and documentation on fair terms and, in several jurisdictions, restrict software locks that block the use of genuine components. Enforcement remains the open question, since compliance is easy to satisfy on paper.