Will the mobile phone brush delete everything in it, such as numbers and text messages?

Brush is to update the existing firmware, so brush may lose some data such as SMS, number, photo and file, but not all brush will lose data.

Brush machines are divided into two types:

Brush the machine thoroughly first-that is, delete all the files in the machine and write the new firmware.

Second, overwrite the printer-that is, the new firmware overwrites the old firmware, but the file data in the system is still there.

Knowledge extension: The safest way is to back up everything you need, which can be backed up to the cloud of some software vendors, so that the data will never be lost.