Why Does My Zte Merit Randomly Shut Down And Turn Back On Threw Out The Day

ive had the same problem with my zte merit and ive finally figured it out its the sim card when you puchased the phone you or either the wal mart employees touched the card which makes it defaulty and causes it to shut off throughout the day how i fixed my phone was returned my phone and sim card to wal mart and had them replace it sim card and all the staff at wal mart will try to take your old sim card and put it in the new phone but no no do not let them do that otherwise your phone will just do the same thing i hope this helps out with your phone problems ppl