MacBook Pro Battery

The batteries on all 2012 models self regulate, self calibrate and don't care when you charge them.

You might reduce their total lifespan if you never ever ever take it off charge. Ideally drain it past 20% remaining (better to run it all the way down) once every few months.

These days, portable batteries are like sealed car batteries. Maybe go in to the shop once a year to have it checked, but otherwise you can forget "caring" for it other than avoiding excessive heat (90 degrees F and up).

Any time you want, Apple can run extensive diagnostics on your battery (for free at the Genius Bar and also complimentary if you pay for AppleCare.)

There could be a couple of things going on.

The first, and easiest, solution is to reset the SMC. Apple has a KB article on that:

http://support.apple.com/kb/HT3964?viewlocale=en_US&locale=en_US

Failing that I would then look at the battery as the cause. Remove it and replace the old one. If it then boots (assuming the old one has ANY charge on it) call the seller and get another battery.

Am I missing anything here?