[Samsung Galaxy S10 Questions & Answers] Lanchon:
do you have backups of the unique-per-device partitions? typically modemst1, modemst2, persist and others.

i'm afraid without those backups you might have lost half of your phone. good thing one SIM card still works. check the IMEIs of the phone in settings: if one IMEI is a testing IMEI, you probably lost it.

in any case, backup your unique partitions NOW!!

just asked GPT4:

android stores per-unit info (IMEIs, serial, various MACs, wifi calibration, possibly other radio calibrations, fingerprint sendor calib, camera sensor calibs?, etc) in certain partitions. which partitions are used or suspected of being used for these purposes? try to name all partitions you know for all manufacturers (no need to specify which manufacturer uses which partition).

Per-unit information on Android devices, such as IMEIs, MAC addresses, and various calibrations, is stored in dedicated partitions on the device's storage. While these partitions can vary among manufacturers and even models, some commonly used or suspected partitions include:

modemst1 and modemst2: These partitions often contain radio and modem-related information, including the IMEI.

fsg: This partition can also contain radio and modem-related calibrations.

m9kefs1, m9kefs2, and m9kefs3: Used on some Qualcomm-based devices for modem and radio information.

persist: This partition often stores various calibration data, like sensor calibrations (proximity, gyro, etc.), Wi-Fi, and Bluetooth MAC addresses.

misc: This partition can contain a variety of device-specific information and settings.

ssd: Sometimes used for storing security-related data.

drm: This can be used for DRM (Digital Rights Management) related keys and data.

sec: Contains security-related data on some devices.

factory: On certain devices, this partition may hold calibration and factory data.

calibration: On some devices, this partition is dedicated to various calibration data.

sensorst1 and sensorst2: These could be present in some models for sensor-related calibration and data.

proinfo: Some manufacturers use this partition to store production-related information, which might include serial numbers.

nvdata: This partition sometimes contains IMEI and other telephony-related data.

It's important to note:

The names and purposes of these partitions can differ among manufacturers and models. Not all partitions listed here are present on all devices.

Directly modifying or erasing these partitions without proper knowledge can result in a device becoming non-functional or losing its certifications (like losing network connectivity due to a wiped IMEI).

Partition names can be proprietary to manufacturers, so the ones listed might not be exhaustive for all Android devices in the market.

If you are looking to work with these partitions or extract data from them, always ensure you have proper backups and be aware of the potential risks.

i add: contents of these partitions are typically encrypted/signed with a per-SoC key, which means that you cannot restore the modemst1 partition of another device and expect to clone their IMEI. to program those things you need the private key corresponding to your SoC, that only the manufacturer has... if they didn't loose it.