It’s standard procedure to factory reset your phone before sending it in for repairs – this keeps your personal data safe while removing any PIN/fingerprint/etc. locks that could prevent the technician from booting up the phone and testing it to see that the repair has been successful.
There is a better way – Samsung’s Maintenance mode from last year and the upcoming Repair Mode for Google Pixels (this is expected to be in the Pixel December Feature Drop). But those are maker-specific features – Google is now implementing a native Android solution that will be available to all makers.
A description of Repair Mode in the AOSP source code
This is called “Repair Mode”, judging by the code that has been committed to the AOSP repository, which was spotted by Mishaal Rahman. The way it will work is that you will enable the mode using your preferred authentication method and then will need to use the same authentication to disable it after getting your phone back from the shop.
While Repair Mode is active, the phone will appear to be running a fresh install of the OS with a new user account that has no data. Your actual account and data will remain on the device, but they will be locked away and inaccessible.
Makers will have the option to disable Repair Mode if they prefer to use their in-house version. This will be a boon for those that haven’t yet developed such a mode.
The feature isn’t finished yet – Repair Mode is already integrated in Android 14 QPR1 beta builds for Pixels, but there should be an app that guides the user through the process of enabling the mode and that isn’t ready yet.
Google is basing Repair Mode on the Dynamic System Updates feature. Normally, this allows you to download a new Android image and run it as a guest OS without overwriting your current installation. It’s a great way to run and test a Generic System Image (GSI). For repair mode, however, DSU will just boot up the original OS image, but with a fresh user account set up.
This will give the repair technician access to the phone’s hardware to test what works and what doesn’t, just like on a factory reset phone. However, restoring your data when you get your phone back will be much easier than dealing with Android’s backup system.