If a phone motherboard is opened and replaced with another motherboard, the old motherboard will still retain all the data that was stored on it at the time of removal. The data on the old motherboard does not get automatically erased or wiped just because it was replaced with a new one.
In the context of a service center or repair facility, they might keep the old motherboard for various reasons:
Data Recovery: If the original motherboard was replaced due to a hardware failure, the service center might attempt data recovery from it to retrieve any important data that was not backed up by the user.
Warranty or Repair Documentation: Some service centers may keep the old motherboard for documentation purposes, especially if the device is under warranty or has undergone a repair covered by a warranty. This helps maintain a record of the repairs and the parts used.
Recycling or Salvaging: In some cases, service centers may refurbish or recycle old motherboards to be used in repairs for other devices with similar issues. This can be a cost-saving measure.
However, it's important to note that keeping the old motherboard with user data can be a privacy and security risk. To protect sensitive information, users should ideally erase all data from the old motherboard or request that the service center securely dispose of it.
As a precautionary measure, before sending a device for repair or replacement, users should back up their data and perform a factory reset on the device to remove personal information and prevent potential data breaches.