[Lenovo Vibe K5 Plus Guides, News, & Discussion] lexiyuri:
Guide to install Lineage OS 16.0 with root, recovery and unlocked bootloader on Lenovo Vibe K5 A6020I36 by lexiyuri

0. Download and uncompress all the essential included files (TWRP recovery, minimal adb and fastboot, lenovo drivers) included in my androidifilehost link:

https://androidfilehost.com/?w=files&flid=303569

Download the Lineage OS 16 from here (thanks to harry8242):

https://androidfilehost.com/?w=files&flid=282516

dont forget to choose latest Lineage OS 16 compilation

Download the Gapps from

https://opengapps.org/

(choose Android 9.0, arm64 and stock options)

Download the latest SuperSU version (flashable zip package) from here:

http://supersuroot.org/downloads/SuperSU-v2.82-201705271822.zip

Important: dont forget to copy the Gapps, supersu and ROM inside a micro sd card before start!!

1. Make a entire backup of your device, syncing Google and WhatsApp accounts before doing something.

Remember: you are going to erase your Stock Lollipop version in your k5!!

2. Install the inclued Lenovo Drivers

from the folder named latest_usb_driver_windows_2

and the drivers in the executable file named LenovoUsbDriver_autorun_1.1.15_user.exe

For Windows xp to 8.1: proceed to follow on screen instructions

Note for Windows 10 users: this OS enforces driver signatures by default. This can be disabled to install drivers that are not digitally signed. Use the following steps to disable driver signature enforcement in Windows 10.

Click the Start Start menu and select Settings.

Click Update and Security.

Click on Recovery.

Click Restart now under Advanced Startup.

Click Troubleshoot.

Click Advanced options.

Click Startup Settings.

Click on Restart.

On the Startup Settings screen press 7 or F7 to disable driver signature enforcement. Your computer will restart and you will be able to install non-digitally signed Lenovo drivers.

3. Install Minimal ADB and Fastboot: double click on the adb setup file included and follow on screen instructions

Alternatively you can download Minimal ADB tool from https://androidmtk.com/download-minimal-adb-and-fastboot-tool or choose the included in compressed

Also you can install Android Studio SDK from its official source in order to use the ADB and fastboot tools

https://developer.android.com/studio/?gclid=EAIaIQobChMIpdiIlpfh5QIVks13Ch2bUw8REAAYASAAEgJW9PD_BwE

4. To ease things, copy the Recovery file (twrp3230.img) into Minimal ADB Program files folder (check before if your program files folder are 32 or 64 bits).

5. Unlock bootloader for lenovo Vibe k5

Enable the Developer Options. To enable the Developer Options, go to settings => About => Software Information => More => Tap on the Build Number around 7-8 times until you see a message telling you "developer options enabled"

Go back to settings and now enable the OEM Unlock by going to Settings => Developer Options and tap "Enable/allow OEM Unlock" and after tap in the "Enable/ Allow usb debugging" option.

I want to clarify in this point: Lenovo doesn't offer an official way to unlock bootloader. Now, connect your phone to the PC.

In your Minimal ADB fastboot program files folder open a command prompt (cmd window) by pressing Shift Key + Right Mouse Click, now type the following command line in your command window

adb devices

(This is to verify your device is being recognized and shows a code or identifier)

Note: if you see a pop up to allow USB Debugging on your phone, Click OK

After that, type the following command below to reboot your phone to bootloader

adb reboot bootloader

Your phone will reboot into bootloader and enter to the fastboot at the same time.

Fastboot screen shows green lenovo logo, a white background and a tiny message saying if you press longer the on/off button you will restart the phone.

Please, make sure your phone shows the bootloader locked and then type the command below to make sure fastboot drivers are installed properly.

fastboot devices

(This command will list the connected devices. If your phone serial number shows up you can continue, but if the phone is not listed, your drivers are not installed correctly. Fix that issue and then continue.

Now, unlock the bootloader with this command line

fastboot oem unlock

Important: this command returns an error code saying that remote oem is not allowed, just like the following one

FAILED (remote: oem unlock is not allowed)
finished. total time: 0.002s

For some reason I did all the entire process without problems. May be Lenovo Vibe K5 is unlocked by default, so, it doesn't matter if the message says you can't do the unlocking. Continue to the Step 6

6. Install the TWRP recovery 3.2.3-0

Type the following command in order to install the recovery and press enter

fastboot flash recovery twrp3230.img

(this line installs the twrp permanently)

Optional: you can just run the recovery temporarly using this line

fastboot boot twrp3230.img

The fastboot boot command line lets you inside the twrp recovery mode window. Also, you can enter to the recovery mode pulling out the battery, pressing vol +, vol - and power all that at the same time.

7. Installing Lineage OS 16.0 -Android Pie 9.0-, Gapps and SuperSu (make root) flashable packages.

First then all, make the reglamentary wipes (one by one) without restart/reboot the phone

wipe system (this will erase the Stock Lollipop)
wipe data (this will erase pictures, WhatsApp folder, Download folder, data apps, wifi passwords, configurations and so on)
wipe cache
wipe dalvik / art cache

In the main twrp window, tap the Install option, locate your microSD tapping in the select storage to activate the external SD.

Now search the files into the SD, pressing in the "up a level" zone and after you reach it, install the following things in the exact order:

Choose the Lineage OS 16 Rom zip file (swipe to confirm) and wait. Dont restart the phone.

After that, choose the Gapps zip file, swipe again to confirm and wait.

Finally, choose the SuperSu zip file you downloaded, do a swipe, wait.

If you want, its possible install all the zip files as a bunch using the "add more zip option" that twrp offers to you, but I prefer do it each one by one.

8. Do a final wipe choosing "wipe Dalvik and Cache".

9. Now choose the restart/reboot option. Wait for the phone initial setup (around a couple of minutes)

10. Configure the phone with your android account preferences. install your favorite apps, sync your info, etc.

Important: during the configuration, the Pixel launcher can fail. So, choose trebuchet as the default launcher.

11. Configure the SuperSU, install it, and verify the root with the Root checker app (you can found it in the Play store) and you are done!! Enjoy!!

== Special tip to enable the TWRP recovery option in the on/off/restart menu===

12. Once you have finished the set-up in your phone enable the Developer options into Lineage OS following this route:

tap in the drawer little configuation wheel ==> System ==> about phone, go to the last option and tap around 7-8 times in the Rom compilation number until you receive the toast message telling you "developer options enabled".

Return to the main system screen options, tap in System, then tap in advanced, and finally tap in the developer or programmer options, activate them and enable Advanced Power/reboot Menu

13. Finally, hold power button, choose restart, then you will see all restart options including the restart to the recovery .