How can I restore my iPod Classic 5th Generation 30GB?

I am trying to restore my iPod Classic 5th Generation 30GB. I have the battery replaced and the hard drive. I had to replace the screen recently because the original broke in a failed reopening attempt. When I got the new one all hooked in the screen lights up but the screen is blank with no text or sound.

I have unplugged and plugged the screen cables multiple times to no avail. I have tried the Hold Switch trick and while that does light up the screen, that's all it does.

I did have an issue before replacing the screen which was that the iPod would go in a constant loop cycle. It would boot up, say connect to iTunes then turn off and start up again in a loop. When I connect it to the computer is not on long enough to restore and setting it into "Utility Mode" doesn't work either. I would Force Shut Down and then it would automatically start back up again.

I have read that it may be the motherboard but wanted to check it there was anyone in the year 2025 that could help me.

I can reply with anything you need for clarification but I really want to use this iPod again! Please help me!!

[Re-Titled by Moderator]