If you install the beta version through the Play Store do you then have the option to leave the beta programme? My guess is that the Play Store thinks you are enrolled in the beta programme and that's why it installs that back.

There should be no special trick to uninstalling a user-installed app. But to be sure, clear the app's data before uninstalling and then check there is no folder left in your internal storage that's related to this app (if there is and you want to keep the contents, renaming it should be as effective as removing it). I'm afraid I don't know more because I've never installed Snapchat.

Another thought: have you tried using ADB to uninstall it?

(Incidentally I don't know why you think you need to reactivate a phone after a factory reset: on most networks on the planet you just put your SIM in a phone and that's it, and even on those weird legacy CDMA networks I wouldn't expect reactivation to be needed as the MEID won't be changed by a reset. But equally this shouldn't need a reset to fix it).

 

Yeah, I know of Aptoide (and have mixed feelings about it: I'm sure some repositories there are OK, but they've also hosted malware and pirated apps and it takes a lot to gain my trust after that).

As I added in an edit above (maybe refresh the page) have you tried using ADB to uninstall it?

 

Unless you somehow installed it to system uninstalling it will mean uninstalling, end of story. If you did install it to system then with an unrooted device you'd not actually be able to uninstall it, and I've met, albeit many years ago, cases where an app that had been moved to system appeared to uninstall but would come back if e.g. you rebooted the phone. But of course you should also need root to install anything to system - though Android 5 may have vulnerabilities that would allow this without rooting the device, and as noted I don't entirely trust anything downloaded from Aptoide.

On that note though, if the problem were that it has somehow been installed to system a factory reset wouldn't fix it: that just erases user-installed apps and data, and does nothing at all to the system partition. So before you resort to a reset you should try to work out what the real situation here is.

A couple of things to try:

1) reinstall it then try rebooting into "safe mode". That should disable user-installed apps, so if SnapChat still works in that mode then your phone thinks it's a system app (though if SnapChat is invisible I'm not sure that definitely proves that it's not installed to system: after all, we know it is giving you the option to uninstall, so the phone clearly doesn't regard it as a system app in other respects).

2) try uninstalling it and then reboot the phone. If it appears to have reinstalled that will almost certainly mean that it is in the system somehow.

The reason I'm focussing on this is that the apk just lying around by itself won't result in the beta version being installed. It needs to be in a specific place where the installer would find it and (somehow) not find the version that the Play Store downloaded - though if somehow a file were in that location then a reset might be your best bet at clearing it. But I don't think that would explain why an apk install fails, which is why i'm wondering whether the problem is that it's not actually uninstalling at all (I don't suppose you noted what error message the apk install produced when it failed: that might give a clue).