Phone powers up completely but screen won't leave logo screen

Ok so I have a galaxy alpha G850a that I replaced the screen/ digitizer on and is now fully loading to the point where I can here the notifications and such how ever the screen won't leave the Samsung galaxy alpha screen. I have tried loading the recovery boot menu and it won't completely load shows the blue recovery boot in the top left corner but won't go past that and it will load into download mode and actually show that screen any help or info at all would be appreciated thanks.