How to fix a Macbook Pro (late 2013 model) with liquid damage?

I bought a refurbished 13" Macbook Pro (late 2013 model retina) from the Apple store website in Sept 2014. It worked great till last month, when I had some water leak out in backpack and get through the ports in the Macbook.

I believe it has affected the logic board which connects the power port to the battery. When the system is plugged into the power adaptor, it works normal. But, as soon as the power adaptor is unplugged, the laptop shuts down as battery charge can't get going. The diagnostics are showing that the battery should be replaced.

I took the laptop to the Genius Bar and was told that there is a flat fee for liquid damage repair - $795. I bought this refurbished laptop for $1300 and paying $795 seems quite expensive. I can continue to use it with the power plugged in, but it reduces its usability considerably. Also, once in a while the power cable gets disconnected shutting down the system unexpectedly.

I called my renters insurance as well, but they did not cover the claim. I may have to just bite the bullet and get it repaired, but I was wondering if anyone has any suggestions on if there are any other options that I have to fix this?