How to Install a Custom ROM on Any Android Phone (Example: Lenovo K6 Power With LineageOS)
by JustcallmeK in Circuits > Mobile
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How to Install a Custom ROM on Any Android Phone (Example: Lenovo K6 Power With LineageOS)

Android phones are powerful, but many times the stock software (called the stock ROM) feels limiting. Maybe your phone doesn’t get updates anymore, is bloated with apps you don’t use, or you just want more control.
This is where custom ROMs like LineageOS, Pixel Experience, or crDroid come in. They replace your stock Android system with a new one, often faster, lighter, and packed with customization features.
In this guide, I’ll explain the universal method to install a custom ROM on almost any Android device. I’ll be using a Lenovo K6 Power with LineageOS as my example, but the process is nearly the same for most phones.
Disclaimer: Unlocking bootloaders and flashing ROMs may void your warranty and can brick your phone if done incorrectly. Follow instructions carefully and proceed at your own risk!!!
Supplies
A compatible Android phone (check if your model has a ROM available).
A Windows/Mac/Linux PC with internet access.
A USB cable for your phone.
ADB & Fastboot tools installed on your computer.
The custom ROM (e.g., LineageOS, Pixel Experience).
Custom Recovery (TWRP) for your phone.
Google Apps package (GApps) if you want Play Store & Google services.
At least 60% battery on your phone.
Backup Everything! (If You Need Your Old Files, Etc)
- Installing a custom ROM will erase your data!!
- Backup contacts, photos, and files to Google Drive, SD card, or PC.
- If possible, take a full system backup using your stock recovery.
Unlock the Bootloader

The bootloader is locked by default to prevent modifications. To flash a ROM, you need to unlock it.
- Go to Settings > About Phone > Tap Build Number 7 times to enable Developer Options.
- In Developer Options, enable:
- OEM Unlocking
- USB Debugging
- Connect your phone to PC, open a command prompt in ADB folder, and type:
- (This should list your device.)
- Reboot into bootloader:
- Unlock the bootloader (this wipes your phone!!):
- or on newer phones:
- Confirm on your phone screen.
Now your phone’s bootloader is unlocked :-)
Install a Custom Recovery (TWRP)
Custom recovery is required to flash ROMs, Google Apps, and root packages. The most popular is TWRP (Team Win Recovery Project). Let’s install it properly.
3.1 Prepare Files
- Download the correct TWRP .img file for your phone (example: twrp-3.7.0_9-0-karate.img for Lenovo K6 Power).
- Place it in the same folder as fastboot.exe (e.g., C:\adb).
- This makes commands simpler.
- Alternatively, you can keep it anywhere and use the full path.
3.2 Boot into Fastboot Mode
- Power off your phone completely.
- Hold Volume Down + Power until you see the Fastboot screen.
- Connect your phone to the PC via USB.
3.3 Open Command Prompt / PowerShell in the Right Folder
- Navigate to the folder containing both fastboot.exe and your TWRP .img file.
- Hold Shift + Right-click → select Open PowerShell window here (or “Open Command Prompt here” if available).
3.4 Verify Connection
Run:
If successful, you’ll see a device ID like:
If nothing appears, check USB cable, drivers, or enable USB debugging.
3.5 Flash TWRP
Run one of the following methods:
Option A: Using full path (safe for all users):
Option B: If TWRP is in the same folder as fastboot.exe:
You should see OKAY messages confirming the flash.
3.6 Boot Into TWRP Immediately
Important: Stock recovery can overwrite TWRP if you boot normally after flashing. To avoid this:
- Boot into TWRP right after flashing using:
(or manually by holding Volume Up + Power).
- You should now see the TWRP interface (blue/grey screen with Install, Wipe, Backup options).
Now your phone has TWRP installed and is ready to flash LineageOS, GApps, and Magisk.
Wipe the Old System (Dalvik, Cache, System, Data)



Before flashing a custom ROM, you need to clean up the existing system files. This prevents bootloops, crashes, or leftover junk from the old ROM.
4.1 Boot into TWRP
- If you’re not already in TWRP, power off your phone.
- Hold Volume Up + Power until the TWRP recovery screen appears.
4.2 Go to Wipe Section
- In TWRP, tap Wipe.
- Then tap Advanced Wipe.
4.3 Select Partitions to Wipe
Check the following boxes:
- Dalvik / ART Cache
- System
- Data
- Cache
Do NOT select Internal Storage (this contains your ROM .zip, GApps, and files).
4.4 Swipe to Wipe
- Swipe the slider at the bottom to confirm.
- This will erase the old Android system while keeping your downloaded files intact.
4.5 Why This Step Is Important
- Dalvik/ART Cache: Clears old compiled app code.
- System: Removes the old Android OS.
- Data: Removes apps and settings from the old ROM.
- Cache: Clears leftover temporary files.
This ensures a fresh environment for your new ROM.
Now your phone is completely clean and ready for the ROM installation in Step 5.
Flash the Custom ROM (LineageOS Example)



Now that your phone is clean, it’s time to install the new ROM. This step replaces your old Android system with a fresh custom one.
5.1 Transfer Files to Your Phone
Make sure you already copied these .zip files to your phone’s internal storage or SD card:
- ROM .zip (e.g., lineage-20.0-2025-01-01-karate.zip)
- Google Apps (GApps) .zip (optional, only if you want Play Store & Google services)
- Magisk .zip (optional, if you want root access)
5.2 Flash the ROM
- In TWRP, tap Install.
- Navigate to the folder where your ROM .zip is stored.
- Select the ROM file (e.g., lineage-20.0-2025-01-01-karate.zip).
- Swipe to confirm flash.
- This will take a few minutes.
5.3 Flash GApps (Optional)
If you want Google Play Store, Gmail, etc.:
- Still in TWRP, tap Install again.
- Select the GApps .zip file.
- Swipe to flash.
Without GApps, you’ll only have the barebones ROM (you can use F-Droid or Aurora Store as alternatives).
5.4 Flash Magisk (Optional)
For root access:
- Tap Install.
- Select the Magisk .zip file.
- Swipe to flash.
5.5 Flashing Order (Important)
Always flash in this order for best results:
- ROM
- GApps
- Magisk
5.6 Wipe Cache/Dalvik (Optional but Recommended)
After flashing, TWRP may prompt:
“Wipe cache/dalvik?”
Select Yes.
This clears temporary files and prevents minor boot issues.
Your phone now has the custom ROM installed and is ready to boot into the new system. Next, we’ll reboot and set it up.
Reboot & First Setup

Now that you’ve installed your custom ROM (and optionally GApps), it’s time to boot into the new system.
- In TWRP, tap Reboot → System.
- The phone will restart and begin loading your new ROM.
Important Notes:
- First boot takes longer than usual (sometimes 5–15 minutes). Don’t panic — the system is optimizing apps and preparing the new environment.
- If the boot screen (boot animation) takes more than 20 minutes, you may be stuck in a bootloop. In that case, go back to recovery and re-check whether you:
- Flashed the correct ROM for your device.
- Wiped system/data/cache properly.
- Installed GApps (if required).
- Once the setup screen appears, follow the on-screen instructions:
- Connect to WiFi.
- Sign in with your Google account (if you installed GApps).
- Set up fingerprint/lockscreen and restore apps if you wish.
Tip: After the first boot, give your phone some time (10–15 minutes) to settle down. It might feel slightly slow at first while background processes finish.
Congratulations! You’ve successfully installed a custom ROM on your phone. Now you can enjoy new features, updates, and a fresh look beyond what your manufacturer originally provided!!!