This guide shows how to install CalyxOS on a Google Pixel 4a (5g) without relying on the device installer provided by the CalyxOS team. Maybe you do not want to or can not execute the device-flasher on your system. Maybe you just want to go through all the steps yourself.
The setup guide is created based on the procedure described in flasher.go (Version 5cb204eb). I assume not all steps are stricly necessary, but I just repeated the steps, which are taken by the device flasher. Make sure that only the android phone where you want to flash CalyxOS is connected.
Although this guide mentions a specific device, the process should work for all devices, which support CalyxOS. Use at your own risk.
Not strictly needed, but I would suggest creating a folder to store both the platform tools and the factory image there.
Download the factory image of the device you want to flash from https://calyxos.org/install/, verify digest and then unzip it into your created folder (no subfolders).
Download the correct platform tools, which can be found by going to the (gitlab code) of the installer, find the function getPlatformTools and download the right version for your operation system from google. Once again, verify digest and unzip the downloaded file directly into your created folder (no subfolders).
If you have adb installed on your system, make sure that adb is not running by running the command adb kill-server. Now use the adb executable, which you downloaded as part of the platform tools, to start the server by running ./adb start-server.
Unlock your bootloader by running ./fastboot flashing unlock.
After you have unlocked the device you should be able to flash a custom rom by executing all the steps outlined in the flash-all.sh file in sequence. If you flash CalyxOS onto a different device, change the img files used accordingly.
./fastboot flash bootloader bootloader-bramble-b5-0.4-8048800.img
./fastboot reboot-bootloader
./fastboot flash radio radio-bramble-g7250-00188-220211-B-8174514.img
./fastboot reboot-bootloader
./fastboot erase avb_custom_key
./fastboot flash avb_custom_key avb_custom_key.img
./fastboot --skip-reboot -w update image-bramble-sp2a.220505.002.zip
./fastboot reboot-bootloader
After all steps were successful, you can relock your bootloader by running ./fastboot flashing lock.
Reboot your device by running ./fastboot reboot.