It doesn’t seem like much, but it definitely requires some preparation and knowledge. I won’t detail all the steps in here, there are many tutorials on the internet. But it’s just a little recap with useful links and info.
I’ve mainly followed this guide (but it’s in french).
Backup your files
Many ways to do that. There are apps like Helium or Titanium Backup.
Google can save your data too.
You can also use the adb command to create backups from your computer (tutorial in french, easy to follow, it’s just command lines).
Connect your phone to USB and check all folders, especially the Pictures folder as everything will be wiped.
Unlock your phone
This will wipe the data of your phone. No other solution here, just do it. Tutorials are easy to find on the internet. I used this one.
I would recommend to reboot the device completely. It might have avoid my bootloop issue (see next part).
Install custom recovery
TWRP is the most famous one, so I chose this one. Go to the official page to download the img file (this is specific for the Nexus 5, the list of other devices is there). Instructions for the Nexus 5 are available on the site too.
I had an issue with the install, not sure if it’s because of the version (3.1.0 at that time) or my install file which was corrupted. But I ended up with a bootloop, but with fastboot still available.
After some research, it’s actually easy to fix that up. I found that thread in XDA forums, where a member says he followed that other guide to put his device back on the road (just replace stuff with Nexus 5 files and you’re all good).
Phew… I must say I was a bit stressed after seeing my Nexus 5 in a bootloop !
Boot to TWRP
Boot to fastboot (hold volume down + power buttons). Choose recovery with the volume button and press power to choose recovery.
Wipe those partitions:
- Dalvik / ART Cache
Download the ROM file from the official Lineage OS site.
When in TWRP, the USB storage of your device should be available from your computer. You can copy the Lineage OS zip file to your phone.
I also put the md5 check file so TWRP can check the integrity of the file before installing it. If your rom filename is lineage-14.1-20170328-nightly-hammerhead-signed.zip, create a text file named lineage-14.1-20170328-nightly-hammerhead-signed.zip.md5, open it with a text editor and put the MD5 hash inside it. Be sure to copy it alongside the Lineage OS rom file on your phone.
Install it using the Install option in TWRP. Once done, wipe the cache as recommended by TWRP. Tap TWRP icon on the top left to go back to TWRP menu.
Install Google Apps via Open GApps
Go to http://opengapps.org/ to download the Google Apps package. The Nexus 5 is using an ARM processor. Note that I tried to install the Stock package, but it failed because of the size of the System partition being too small. I had to go down to the Micro package to be able to install the apps.
Same thing as above, put the zip file on your device, along with the md5 file (you can download that file directly from the open GApps site). Install it using TWRP, wipe the cache, and you’re done.
Reboot and enjoy
Reboot the phone and let LineageOS boot. It will take some time to boot at first.
Restore the files using whatever method you chose. I personally just restored things from my Google account. I don’t mind loosing some data as I didn’t have anything important.