I will do that when I pop it back open. I got it working by bending the tab a bit so when it closes it pushes in the right way. All contact points are accurate. However during all my troubleshooting the speaker worked its way off the pcb. FUCK!  Don't worry it's back on now !  Thank you guys!

You may need to use a wire then. You basically need the entire ground plane on the back to connect to the ground plane on the front that connects to that tab.

Ok added the solder. Same thing.

Haha had you typed out a similar essay?

man, I'm slow.

Attempting now.

And actually, now having an LCD PCB in my hand it supplies ground to part of the LCD, the center capacitor and it is the only ground signal for the speaker.

Yep! Just realized I said right instead of left! Try adding some solder to it on both sides.

When looking at the back of the PCB is it the prong in the middle on the left side? If so this ground tab actually acts as one very necessary "via" that supplies many of the capacitors with their ground signal.

You can try:
Adding a good amount os solder to both sides of the prong and hope it fills in the gap.
Or if the PCB is broken in this spot then you would be better off trying to use a wire. Scrape off some of the material over the copper(solder stop) near the ground tab, apply solder and simply use a wire.

This should fix it. Let me know if this works!

Yes that prong. I put the backlight in powered it on and it worked. Screwed it back together and noticed it was dimmer. When I applied pressure to the right side of the gameboy right underneath the screen cover that's when the screen got brighter. So opened it back up and made sure the backlight was seated correctly. It was so I plugged it in and turned it on then tried to see what was happening when I put pressure on that right side. I pin pointed it was the ground prong. If I pushed from bottom side of the prong up towards the top of the pcb very gently btw it brightens up and stays that way. When I let go a second or so it goes dim again.

You mean the prong that connects to the back PCB when the gameboy is assembled? You're working on this with the gameboy open?

I just took a backlight out of an old dmg (solid black horizontal line in screen) and put it in a new gameboy. When I power it up it is dimmer than it should be. I noticed when I bend the ground prong on the front pcb it makes the speaker pop and the backlight brightens. Any ideas? I checked my soldering and everything seems ok. Good connection and no wires are touching.