Put the phone one and confirm if the Home button works. If it doesn't you have to change it. If the button works then it may be the lightning port - 1st try to clean in inside if still doesn't work - change it. Let me know how it goes.
According to the specifics on Samsung website, you can't upgrade RAM so easy because is LPDDR3 on soldered onboard. As for the hard drive, it's got eMMC so that means is also soldered to the board. Conclusion: 1. To make it faster, you can upgrade RAM only if you have experience into desoldering/ soldering this stuff. 2. To increse storage, you can upgrade the eMMC - same you need experience. But you can skip this and just get a C-port flash drive to increse you storage.
1. First of all switch off the device by pressing the Power button. 2. hold down Volume Up + Power button for about 10 seconds. 3. You can release held keys when you see the Android Robot. 4. If you see a menu, navigate with UP/DOWN keys and go for a factory reset. 2nd Method. 1. Enter the Recovery Mode hold down the Power key for a short while. 2. From the menu choose "Wipe Data/Factory Reset" by using Volume buttons to scroll and Power button to select options. 3. Tap "yes" to confirm the operation if you are certain you want to clear all your data. Use the Power button to accept option "reboot system now".