so after factory reset that i needed to do because my phone was lagging really badly, i saw something that made me angry, i couldnt install any app or update it, it said error 504 and i saw a post where they said to remove its updates to factory version 6.xx and i rememmber having much higher version and the problem continues but it doesnt say error 504, now it says something with server and the google play store doesnt want to update it self, and when i tried to update it with apk it said installation failed, i am lost at this point, i would be glad if someone helped me