Turn off the phone and turn it on while holding down the Home, ON / OFF and Volume + buttons.

It is sewn into the kernels of custom firmwares and therefore it will appear on your device after installation.

Clamp all device buttons simultaneously and wait for the screen to turn off (usually takes ≈10 seconds) and then release all buttons.

Go to Settings>“About phone” and press “Build number” 7 times.

At the same time hold and hold the Home and Volume - buttons.

Not.

Follow this instructions to restore them.

In firmware, they are already built-in. You can activate them in the settings for developers in the item “Superuser mode”.

Not. Custom firmware will not be installed due to the verification of archive signatures built into the recovery.

Using the “Titanium Backup” program, but in very rare cases, errors may occur in the operation of restored applications.

Install it through Odin. All details in related topic

No, cleaning is optional. Just install it through the recovery on top of the existing one.

GApps (Google Apps) are Google’s apps and services.

Copy file tun.ko of system / lib / modules at system / lib / modules / autoload and restart the phone.

For some firmware in the settings, the “3G” mode means “2G + 3G” with the priority of the latter. You can fix this by choosing 3G mode in the settings, then dialing the code “* # * # 4636 # * # *” in the dialer, in the window that appears, go along the path “Phone Information”>“Set Preferred Network Type” and select “WCDMA only”

Overclocking is carried out using the built-in ChronoKernel firmware by increasing the processor frequency (by default 800 MHz with the possibility of increasing to 1245 MHz) and using a script for overclocking DDR (more details under the "Useful" spoiler).

This happened as a result of damage to the “modemfs” section in the phone. To return everything to its place, you need to flash the modem you need for this reference .

Note!
If you selected modems for CWM, then you can sew them through TWRP, but you have to do this 2 times. After the first installation, in the settings, the firmware of the communication module will be defined as “Unknown”, and after the second, everything will be as it should.

Need to follow this instructions

This is the process of resizing memory in some partitions at the expense of others. It is needed because when installing custom firmware in the "system" section there is not enough space to install GApps. Of the presented selection of files for re-allocation of memory, I personally recommend choosing this one - CWM_ReParted_SY820_CA130_DA1800_SD1000

1. Download the archive from CWM:Temporary CWM
2. Copy it to the root of the memory card
3. Go into the recovery (hold down the Volume +, Home and Power buttons simultaneously)
4. Use the volume buttons to select apply update from sdcard, the power button - confirmation
5. Select the archive with CWM and install it.

1. Install the stock firmware Android 4.1.2 (if already installed, skip this item)
2. Download the firmware, GAPPS for the Android firmware version (5.1 or 6.0, put the gapps package at your discretion), as well as the Chrono corer2.24.7
3. Copy the firmware, GAPPS and kernel to the root of the memory card
4. Run a temporary CWM, install the Chrono r2.24.7 kernel, restart the recovery
5. Back up the partitions: click Backup and select Data, Boot and System
6. Next, click wipe and select system, data and cache
7. Click on Install, select the archive with the firmware and GAPPS
8. Confirm installation
9. Reboot the device

Not in every case, you can just update, sometimes you need to install from scratch.
Firmware update examples:
1. Transition SM12.1->CM13. Since the firmware is incompatible, you need a "clean" installation, for this you need to make wipe system, data and cache in CWM / TWRP. Similarly for
SM13->CM12.1.
2. When updating CM12.1 / 13->CM12.1 / 13 from another developer, you need a "clean" installation, for this you need to make wipe system, data and cache in CWM / TWRP.
3. When updating CM12.1 / 13->CM12.1 / 13 from one developer, you don’t need to do wipe (unless the developer asks for it).
Note
WhenCM13 by SergeylThere are 2 types: Standard and Full.
Upon transition CM13 Standard->CM13 Complete, you need a "clean" installation (because the firmware is incompatible), for this you need to make wipe system, data and cache in CWM / TWRP.
Similarly with CM13 Full->CM13 Standard.
When updating the firmware of one type, wipe does not need to be done (unless the developer asks for it).

• LineageOS 15.1 (fromSergeyl)
  
• LineageOS 15.1 (fromChronoMonochrome)