Why won't my iPhone 6S turn on?

iOS 12.1.4, iPhone 6S 64GB Black, Non-Jailbroken

Hey everyone,

Unlocked iPhone, opened YouTube++ (Sideloaded application). It proceeded to crash on launch and turn off my iPhone. It briefly displayed a screen that was glitchy-looking and had a weird line on the top right. (Kernel panic?).

I tried turning it on. Was met with Apple logo and it was frozen at the logo until I turned it off. Was able to go to Recovery Screen but I kept trying to turn on/off the iPhone because I wanted it to boot to iOS. Now, the phone won’t even turn on.

Currently using an iFixit battery inside the iPhone.

The iPhone’s Condition:

• Unable to turn on.
• Plugging it in to charge doesn’t turn on the phone.
• Unplugging the internal battery and plugging it back in doesn’t fix the issue.
• Attempting to boot in DFU Mode or Recovery Mode won’t work because phone won’t turn on.