iPhone 2G won't boot up

Hey guys, I have recently gotten my hands on an iphone 2G which apparently has a software issue after installing an ios update (stated by the seller). I figured I can try getting it into DFU and retrieving an older version through itunes. However, the device wont light up unless it is connected to the cable and then it goes into a loop of lighting up with the Apple logo and not much else happening, does not get detected by itunes as well. It will stay that way for 15 seconds and then the logo will remain with the screen light dimmed. The power button does nothing when it's like that, nor does the button combo for DFU.

As this is a bit confusing, I will link a video of the problem. Any help in reviving this absolute legend will be much appreciated, as I do believe the issue to be software in nature.

Here's the video:

https://drive.google.com/open?id=1--E53AAc-OAE3-3ackcLNsXAqkOaVVRS