Gameboy has bootup sound but no screen and battery LED (IPS Screen)

I have an old gameboy with a busted screen but it turns on and plays the boot up sound even though the battery LED is not on... so I replaced it with an IPS screen kit hoping that only the screen is the issue.

Finally got it replaced but still no LED battery light and no screen turning on.

My batteries are fully charged and the battery contacts are clean as well as the back board... at least I think tis clean.

What do I need to do? Is this still fixable or do I need to buy a fully working gameboy