Small horizontal lines on startup

Hello,

My MacBook Pro 15" retina display (late 2013) crashed without any warning. On reboot, the computer passed through the Apple logo without issue to the login screen with my different accounts (personal and guest.)

Upon trying to log into my personal account, however, the load bar would only reach about 60%, whereupon it would not progress any further; additionally, very small horizontal blue lines would cover the entire screen. I restarted my computer; got to the login screen, and the same thing would happen if i tried to log into my guest account.

• I reset the SMC and NVRAM/PRAM; nothing changed.
• I tried starting in Safe Mode, and the load bar reached 100%, but it would not actually complete the load and the blue lines reappeared.
• I tried reinstalling macOS, and this time the blue lines appeared at the Apple logo at about 40-50% loaded.
• I tried running a hardware diagnostic, which worked, but only told me that my battery needed to be replaced soon.

I tried redoing these methods a couple of times, and now it won't even make it to my account login screen, it just stalls out and shows blue lines at the Apple logo.

Any thoughts on what this could be and how I could fix it? Regardless of what the hardware diagnostic said, my father believes it is a hardware issue (and he certainly could be right), but I thought it would be best to crowdsource potential answers before going to the Apple Store to get it checked out.

Photos attached of the blue lines (only on the Apple logo background; unfortunately I didn't think to take photos of the login screens before the computer would no longer load that far).

Thanks in advance.