Let's address the networking issue first.

It sounds like the 'new' player has a custom configuration file which has certain settings messed up, including, a network configuration that is incompatible with your computer. The fact that it comes up as "192.168.0.168" makes it sound like the player's previous owner hard coded that address into its configuration file. Your goal will be to change it so that it's not hard-coded any more, and it will obtain the address through DHCP instead. This can be done via Emplode, or, by directly editing the configuration file on the player's hard disk.

Normally, you would just connect via USB to make the single configuration edit that makes ethernet work, save that change, then go back to doing everything by ethernet after the change is made because after that ethernet will work. But USB is not an option for you right now.

Available options:
- Connect via serial to make the edit. If your computer is a desktop computer, it might still have a serial port. If not, you can probably get one installed. If it's a laptop, you can get USB-Serial adapters. I'd recommend one with the FTDI chipset like this one. That's the one I'm using right now to connect to my empeg serially from my Win 8.1 computer (for times when I need serial port access).
- Temporarily change the computer's configuration to force it to a fixed IP address on the .0. subnet just to get the edit done. Then change it back to DHCP when you're done with the edit. After that, ethernet should work.

You will likely end up needing a serial adapter eventually. But for now, I'd suggest the latter path so that you can get it going quickly.

Next, the button:
- Once you have the player working on ethernet, dig into the player's config file and see if they put some weird IR-translate or other button-futzing stuff in there. Maybe there's nothing wrong with the hardware and it's just a messy config that doesn't work right.