My LG 4G LEON overheats, battery drains fast,runs slow, has verticle lines on screen & screen fades in color. Do I need a new battery or new phone? HELP????

Could my LG LEON 4G LTE smartphone need a new battery, I have had it for about 7 - 8 years, same original battery. Phone overheats at times, which I let cool. And getting black & white lines vertically on the screen. Also the screen fades out to a white / grey picture. Can the battery be doing this,just.started doing this not long ago PLEASE HELP. Cannot afford a new phone at this time.

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What would my LG LEON 4G LTE phone make the screen fade & to get black & white vertical lines?

My LG LEON 4G LTE phone is overheating alot, screen goes to a white/ grayish color & cause white, black, blue & red lines going vertically on screen. What would cause this??