Hello, Tech Expert here, i used to fix everything from TVs to Vapes to Phones, i had my own store a long time ago, i still have my tools and all, i would say this is probably a dead battery problem, if the battery hasn't been charged for a decade, chances are the transistors and capacitors are dead as well, theoretically it could be possible to remove the internal memory and put it on a working mp4 motherboard, i think i have about 32 of them left somewhere in my attic, i'm willing to give it a try and repair it/extract the data off of it for you, depending on the amount of BTC i'm willing to compromise, 10btc i'll take just 1.

If you're interested, Contact me on my number Via WhatsApp that is in my profile, have it shipped, and we'll work through it!