Why does my screen go from big clock to main screen constantly without stopping?

[AC Question]

screen goes from big clock to main screen constantly without stopping

phone was dropped screen had to be replaced was done but now after a reset phone wont allow anything to be done just keeps going back and forth

 

[B. Diddy]

Welcome to Android Central! Which phone? Do you mean it goes from the lockscreen to the homescreen and back again, without touching it? It sounds like either the screen was not replaced properly, or something else on the motherboard was damaged from the drop. Bring it back to the repair shop and show them what's happening now.