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TRYING TO INSTALL LINEAGEOS ON MOTO G7 POWER

A Comprehensive Guide to Troubleshooting LineageOS Installation on the Moto G7 Power

We understand the frustration that arises when you are deep into the process of installing a custom ROM like LineageOS, only to be met with cryptic error messages and a device that refuses to boot. The journey to liberating your Moto G7 Power from stock Android is usually straightforward, but specific models and partition schemes can create unexpected hurdles. The error messages you are encountering—“is-logical:boot_b: not found” and “Image not signed or corrupt”—are not uncommon, but they point to a very specific misunderstanding of how the Moto G7 Power handles its boot partitions.

In this comprehensive guide, we will dissect the issues you are facing, explain the underlying architecture of the Moto G7 Power (codenamed “Ocean”), and provide a definitive, step-by-step solution to get LineageOS running on your device. We will move beyond the generic instructions and delve into the specific commands and partition logic required for this particular Motorola device.

Understanding the Core Issue: A/B Partitioning and Slot Management

The root of your problem lies in the A/B (Seamless) Updates partition scheme utilized by the Moto G7 Power. Unlike older devices that have a single set of partitions for the boot, system, and vendor images, your device maintains two sets of these partitions. These are referred to as “Slot A” and “Slot B” (often represented as _a and _b).

When you execute the command fastboot flash boot boot.img, the bootloader defaults to flashing the image to the currently active slot. However, the error is-logical:boot_b: not found suggests that fastboot is trying to interact with the boot_b partition while the device’s current state or your command syntax is not correctly addressing the logical partitioning structure introduced in Android 10 and later. Furthermore, the error Image not signed or corrupt is the bootloader’s security feature rejecting the boot.img because it lacks a valid Motorola signature.

The “Image Not Signed” Error Explained

Motorola devices come locked from the factory. While you may have unlocked the bootloader via the official Motorola unlock portal (a mandatory first step), the bootloader still expects images to be signed with a valid key. Official LineageOS builds are not signed with Motorola keys. Therefore, the bootloader will reject a direct flash of the standard boot.img if you do not have a custom recovery (like TWRP) installed first, or if you are not using the fastboot boot command correctly with a vbmeta disable flag.

The fastboot boot Dilemma

You mentioned trying fastboot boot boot.img and seeing the Motorola logo before being kicked back to fastboot. This usually happens for two reasons:

  1. Incompatible Kernel: The boot.img you are trying to boot may have a kernel that is not compatible with your specific firmware version or build number.
  2. Verified Boot (AVB): The device’s Android Verified Boot is still active. It detects that the boot.img is not signed and halts the boot process, rebooting the device back to the bootloader as a safety measure.

Prerequisites: Preparing Your Moto G7 Power for LineageOS

Before we attempt the installation again, we must ensure that the foundation is solid. Skipping these steps is the primary reason for the errors you are experiencing.

1. Unlocking the Bootloader

We assume you have already completed this step, but it is worth reiterating. You must have an unlock token from Motorola. Without this, none of the commands below will work.

2. Installing a Custom Recovery (TWRP/OrangeFox)

For the Moto G7 Power, attempting to flash LineageOS via fastboot commands alone (manual flashing) is risky and often fails due to the A/B partition complexity. The recommended and most stable method is to install a custom recovery first.

3. Understanding vbmeta and AVB Disabling

This is the missing link for many users. To boot a custom ROM or a custom kernel, you must disable Verified Boot. This is done by flashing a vbmeta image with verification disabled.

The Correct Installation Method for LineageOS on Ocean

We strongly advise against manually flashing every partition (boot, system, vendor, etc.) via fastboot unless you are an expert. The cleanest way to install LineageOS on the Moto G7 Power is via TWRP Recovery.

Step 1: Downloading the Correct Files

Ensure you have the correct LineageOS build for the Ocean device model. Verify the MD5 checksum of the downloaded zip file to ensure it is not corrupted.

Step 2: Performing a Clean Installation in TWRP

Once you are in TWRP, follow this exact order to avoid boot loops:

  1. Wipe Data/Factory Reset: Go to Wipe > Advanced Wipe. Select Dalvik/ART Cache, Cache, System, and Data. Swipe to Wipe. Do not wipe the Internal Storage unless you want to lose your photos.
  2. Flash the vbmeta Image (Critical): If you haven’t done this via fastboot, go to the Install section in TWRP, select “Install Image” (bottom right), choose your vbmeta.img, and select the “VBMeta” partition. This disables verification.
  3. Flash LineageOS Zip: Install the LineageOS ROM zip. Swipe to confirm flash.
  4. Flash GApps Zip: Immediately flash your GApps package (if desired). Do not reboot in between.
  5. Flash Magisk Zip: If rooting, flash Magisk now.
  6. Wipe Cache/Dalvik: After all flashes are complete, wipe Dalvik/Cache one last time.
  7. Reboot System: This first boot may take 5–10 minutes. Be patient.

Addressing the Specific fastboot Errors You Faced

Let’s circle back to the specific errors you provided in your request. Here is exactly why they occurred and why the TWRP method resolves them.

Error: sending 'boot_b' (27478 KB) OKAY [0.762s] writing 'boot_b' (bootloader) Image not signed or corrupt Analysis: You attempted to flash boot.img to boot_b (Slot B). The Moto G7 Power bootloader verified the image, saw it lacked a Motorola signature, and rejected it. Solution: The TWRP method bypasses this because TWRP is already a custom recovery that is allowed to exist on the system. Once TWRP is running, it can write to the partitions directly without the strict signature check that the bootloader applies during fastboot operations, provided you have disabled AVB via vbmeta.

Error: fastboot boot boot.img -> Boots to Motorola logo, then Fastboot Analysis: You attempted a temporary boot. The kernel inside boot.img attempted to initialize, but the vbmeta partition still contained active verification flags (or your boot.img was incompatible). The system detected a violation and rebooted. Solution: Flashing the vbmeta image with --disable-verity --disable-verification permanently tells the bootloader to trust any image, allowing the temporary boot to succeed or the permanent flash to take hold.

Troubleshooting: If You Are Still Stuck in Fastboot

If you have followed the TWRP method and are still unable to boot, consider the following advanced checks:

Checking Slot Partition Active

Sometimes the device is stuck on a corrupted slot.

  1. Boot into Fastboot.
  2. Check the active slot: fastboot getvar current-slot
  3. If it says a, switch to b: fastboot --set-active=b
  4. If it says b, switch to a: fastboot --set-active=a
  5. Try the TWRP installation process again on the new slot.

Firmware Mismatch

LineageOS builds depend on the underlying stock firmware version. If you are running an older version of Android 9 (Pie) and try to flash a LineageOS build meant for Android 11/12 (R/S), it may fail to boot. You must update your stock firmware to the specific version recommended by the LineageOS maintainers for “Ocean” before flashing the ROM.

Post-Installation: Ensuring Stability

Once you have successfully booted into LineageOS, there are a few final steps to ensure your Moto G7 Power runs smoothly:

Conclusion

The errors you encountered—is-logical:boot_b: not found and Image not signed—are classic signs of attempting to use raw fastboot commands on a device that requires specific AVB handling and A/B partition awareness. The solution is not to force the command, but to change the strategy. By utilizing a custom recovery (TWRP) and ensuring you have disabled verified boot via vbmeta, you bypass the strict signature checks and partition logic errors.

We hope this detailed breakdown has cleared up the confusion surrounding the Moto G7 Power installation process. With the correct preparation and the steps outlined above, you should be able to transform your device into a clean, ad-free, and highly customizable LineageOS machine. Should you need further tools or root-based enhancements, remember that Magisk Modules is your go-to destination for the best Magisk modules available.

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