can't activate iphone 4

Hi. I tried many ways to activate my iPhone 4 including a hard reset but failed.

What should I do besides bring it into the Apple store?

Is it something to do with a sim card? There is no sim card in my iPhone 4 for now.

I have an iPhone 13 pro max as a main phone but I have an emotional value with this iPhone 4.

I just want it to turn on.