Sega Nomad Pi zero Project reuse Amplifier

hi this is my first post and I'm hopping some one can give me a hand with this project. I ebay purchased a dead SEGA Nomad a few years ago thinking it was a easy fix it turned out to be a dead CPU and blown voltage regulator witch I couldn't get running so I moved on and bought another dead unit witch was a easy fix just desoldering the DC connector back in place and I still have my second Nomad working today unmodified. While looking at all the mods I could do with the nomad I decided to hack up the dead Nomad and install a Raspberry Pi zero w in it, I love the buttons and it has one of the best D-pads I have used in my opinion so I have already figures out how to map all the buttons to the Pi so thats not a problem but I want to reuse the Audio Amplifier because the head phone jack and the volume potentiometer fit perfectly. I really don't no where to start with this Amplifier I don't now how to get power to it because the power board it not in great shape and isn't supplying any power and I'm not sure in how to get sound in to the Amp. literally I want to turn into a external speaker for my Pi zero. any help would be great thanks.

 

tl;dr
break up your sentences

 

thats loads of help cheers

 

Dead cpu and voltage regulator is easy enough to fix. Don't gut a nomad for "yet another raspberry pi mod"