Maybe there is problem in your memory card.replace memory card with another one or use another memory card to see what happens.if not help, then format your mobile.remember to backup important files to pc or pen drive or to other device first.
No I think backup is good 1 day with light-medium usage with internet on.if you playits the hardware that designed that way.you cant light them up.btw there is no need to light up those keys.you just have to know where those keys are, simple heavy games.it’ll be less.turun your data on .and hit the airplane mode an turn it off .so u can use data connection that what I do.