[T-Mobile Samsung Galaxy S 4] tonytien:
Hi aliencds,

You could try installing LineageOS on his phone first before buying a new phone. I've installed LineageOS on my Galaxy S4 and it works great still. The latest LineageOS version that works for the Galaxy S4 is based on Android 7.1.1. I also want to be clear that what I'm about to suggest will require you to erase his phone and I don't take any responsibility for what might happen (though it's tried and true). It'll also remove any of the Samsung-specific ROM features that came with his phone (no more Smart Stay, Smart Scroll, etc).

You don't need to root the phone, but you will need a custom recovery to install LineageOS. I'd recommend you download TWRP from here (make sure to pick the latest version with the file extension that ends in .tar). You can flash that onto his phone using Odin or Heimdall, but I'd recommend Odin because I feel like Heimdall is a pain to use (Heimdall is CLI). Odin does require a Windows computer, though. This XDA thread is a good place for some reputable download links for Odin.

You'll also need the actual LineageOS file (Android 7.1.1) and an OpenGApps package to pull this off. LineageOS for the T-Mobile Galaxy S4 can be downloaded here (pick the latest version). OpenGApps installs the Google Play Store and Google Play Services, and it can be downloaded here. When downloading OpenGApps for the Galaxy S4, make sure ARM (not ARM64) and Android 7.1 are selected. From there, select the package you'd prefer to install. You can pick the aroma package for the ability to select any of the Google apps you want to install, but if you don't pick aroma, it might be best to pick micro, nano, or pico because the Galaxy S4 doesn't really have enough system partition space to handle the bigger packages.

After you download LineageOS and OpenGApps, make sure they're both on the phone -- so you could've either downloaded it straight from the phone itself, or you can download it on your computer and transfer the files over to the phone via USB.

Next, you'll use Odin and Download Mode to flash LineageOS onto his phone.. To put the phone into Download Mode, turn the phone off. Then, press and hold the power button and volume down buttons, then release them when you get the Download Mode screen. Next, plug the phone into your computer, and you'll use the "AP" button in Odin to flash the recovery file that you download from the TWRP website onto the phone.

After that, you'll need to use TWRP on the phone to install LineageOS and OpenGApps via recovery mode. To get into recovery mode, turn off the phone. Next, press and hold the power button and volume up buttons until you see the small "RECOVERY MODE" text in blue in the top left corner of the phone screen, then release the buttons. From there, do a factory data reset with TWRP using its "wipe" button, then install the LineageOS zip, then install the OpenGApps zip. You won't need to reboot in between any of these steps, and especially don't reboot before you install OpenGApps - you might have to go back into TWRP and start all over. But after you've finished flashing LineageOS and then OpenGApps, reboot and set up the phone.

Honestly, the recovery mode and download mode button combinations can be tricky to get right. A video might help you get into those modes better than written explanations will, since a lot of it has to do with the timing.

After you've gotten everything installed, you'll have Android 7.1.1 on his phone with working Google apps. From there, you should be able to get MoviePass to work. Let me know if you have any questions or concerns, especially because this was a pretty brief overview.