How to fix my iPhone 3GS

Ok, so this is my first support thread. Sorry if I do it totally wrong.

I have my friends OLD iPhone 3GS, which has one of the strangest issues I've seen. I have searched the internet for answers, but nothing works. This isn't extremely important, nobody uses the phone anymore, but I want to fix it. Maybe buy it from them and add it to my retro computing collection. Anyway, this is the issue: The iPhone doesn't boot. If you plug it in on a completely dry battery, It gives the apple logo, attempts to boot, and then stops and gives the battery charging symbol like it should. It seems to work normally for about 10 minutes, but then it fails to respond to anything. Now, this is the part that makes it complicated: When I put my ear up to the phone, it makes a "ticking" discharge sound about 4 times per second, then a faint 1/2 second beep, then repeats that 4 times. After, it either stops making any sound or continues make the discharge sound.

I've tried restoring the phone, but it failed with unknown error (9) in iTunes. It is black, and I do not know the exact specs, but I think its a 16GB version, a 600 MHz Cortex-A8 processor, and 256MB RAM. Technically, it has iOS 6.13, but it failed to restore to that.

Does anyone know what this means? What the problem is?

Any help is greatly appreciated!