Original post by: Carlos Oulman ,
Likely a battery issue as it’s an old phone and as stated before, likely it’s never been replace before. We see Apple devices act goofy even if they are plugged in when they have bad batteries. Also as stated, it could just be taking its sweet time to boot up. The real question is, why are you trying to fix this thing? Can’t imagine it will be very usable unless you are restoring it for nostalgic purposes.