Well, the Galaxy S5 was a nice phone when I bought it from T-Mobile in 2015 in Phoenix. Not a fire breather, by any stretch, but nice. Unfortunately, it has become a dog. I’m not sure that it’s the phone’s fault – with Samsung and T-Mobile putting all that “crapware” on it, taking way too much memory all the time. In addition to all that, T-Mobile is responsible for the base Android firmware updates, even though I’ve moved back to Canada and put it on Bell-MTS… and they haven’t updated it in over 18 months. They probably will never update it again.
So, now I’m thinking that I’ll have to do what I did on my trusty old Motorola Atrix phone when it started to dog out some 6 years ago – root it and put Cyanogenmod, or equivalent, on it. No crapware (nothing that you can’t delete anyway), only what you want, and up-to-date Android firmware. Cyanogenmod has morphed into Lineage OS. I don’t recall what the reason for the morph was, but I think it was that the Cyanogen corporation that was formed to maintain & support the O/S, got carried away and did some dumb things (including trying to make their own phone and compete with Apple/Samsung/LG etc.). Anyway, it’s Lineage OS now.
I actually have two identical phones, so I can modify one and not take the hit when I goof up. So I’m actually changing my original T-Mobile S5 phone, and my “newer” phone still has the original firmware. Ugh, it’s so slow that I can barely use it.
The T-Mobile Galaxy S5 is model SM-G900T. Lineage calls it “klte” and firmware for it is at this location on the LineageOS website. Note that it’s not an ARM64 but just ARM architecture.
You first need to root the phone. Go to this article in Tom’s Guide which will show you how to root your phone with a program called Odin. You should be able to boot the original Android firmware, but it will moan and groan about being rooted. Good!
Next you install TeamWin Recovery Program “TWRP”, which is a middle stage loader that allows you to change OSes (“ROMs” in Android parlance). To install TWRP, you use Odin again. You power down your phone, power up with a specific key combination to get into “recovery”, and then blast the TWRP image onto the phone. See this TWRP page to get the image, which right now is version twrp-3.2.3-0-klte.img.tar .
The instructions for Lineage OS installation , but ignore the part about “heimdall”, that didn’t work for me at all. You did all that with Odin. Skip down and use ADB to “sideload” Lineage, Google Apps “GApps”, and LineageOS SU Addon. If you don’t have ADB, here it is. The Lineage image as of today, is lineage-16.0-20190324-nightly-klte-signed.zip . There are links in the instructions over to Google Apps, present version is 20190325. There are several sizes of download, check out the chart of the different sizes. I used “mini”. Then also install the optional LineageOS SU Addon. Do not reboot until all three packages are installed.
It seemed to take forever for the phone to boot, the first time after installing Lineage, GApps and the SU Addon – but it did boot. Have patience.
Once you log in to your Google account, you can restore your applications, etc. In may case, I “restored” it from what was saved by the other phone (grin). I had to re-delete some of the crapware, but that’s a small price to pay.