No Batteries Available ?-How to Check battery health on MacBook Pro early 2011
All the information you get from fancy 3d party is already in your system (that is where they get it from anyway).

Open your About This Mac, more info, system report and find Power:

It will tell you all about your battery.

It looks like this on my system:



Normally the Battery will keep a small reserve charge to be able to report its status to the computer. In your case somehow it was sucked dry completely :) 

The good news is it is the battery, since your SMC is working and everything else is working based on the message "Replace battery". That same message was probably run all the time during your vacation, till the battery was exhausted to the level were the battery build in chip did not have enough power to talk to your OS. As for what caused that drain? did you leave your computer in a sleep mode ?