Several old Nexus devices just don’t support Android 6.0 Marshmallow (and many never will), and that has left some owners of older phones feeling left out. But now, owners of the 2010 (yep, 5 years old) Nexus S might be glad to hear that one developer has managed to put together a build of Marshmallow for the phone. It’s definitely at your own risk, but you can now install this hacky unofficial build of Marshmallow with a little know-how, and here’s how to do it…
The unofficial image comes by way of one Dmitry Grinberg, and his instructions on making the image yourself using the AOSP (Android Open Source Project) are published on his website. That’s theoretically the safer method of installing Marshmallow on your Nexus S, as we can’t prove that Grinberg didn’t tinker with the full working image he provided. The good news is that if you trust him, there’s a full working image available — and installing it is pretty simple.
You can download the image from Dmitry’s website (the download might take a while since he doesn’t seem to have the most powerful servers). He suggests that you use the latest publicly available bootloader when flashing.
Here’s what he had to say about the image on his website:
Nexus S (crespo) got its last update in Oct 2012. It was Android 4.1.2 Jelly Bean. Android M (marshmallow) just came out recently. I decided to port M to crespo for fun, and as a demo that old hardware can in fact run new versions of android. In this article you’ll read about some of the challenges I faced in making this happen and find the information you need to reproduce my results. And for the lazy, I also have a pre-built AOSP Marshmallow image set to download on the bottom of this page. Since Nexus S was originally a Google-Play-equipped device, you can legally install Google Apps on this image and enjoy a full Google Android 6.0 experience on your Nexus S. That part, however, is up to you to do yourself. I am not offering GApps downloads here.
While we don’t have a Nexus S to test it on (who does?), we have confidence that it will work given the many reports from Redditors who have praised both his Nexus 4 and Nexus 7 (2012) ROMs. To install the factory image, simply follow our guide. That guide assumes you already have the ADB tools installed on your computer. If you need the ADB tools, head over and download the Android SDK. The rest of the guide should be pretty straightforward (once you manage to download the image, or create it yourself, of course).