At first I thought it was a bad battery problem so that I bought 2 replacement batteries and replace it. The battery will then drained to 0 from which state I got since bought even plugged onto the magsafe power adapters.
I use my wife charger to try whether my own charger is the culprit, but I can confirm that there has nothing to do with the chargers as both chargers works well with my wife's MBP (late 2011 too).
I then sent for repair to one of the computer for them to have further inspection (I contacted Apple support online and they could give any support for this older model). This has end up to frustration as they could not do anything on the issue and they couldn't even tell what is real problem.
The only thing I can do now to power up the MBP is by dissemble the battery and install on wife's MBP to charge it. After fully charged, install back on mine and turn it on with no issue. The weird thing is that if the battery installed is fully 100% charged and connected to magsafe, it won't drain?! This is the best I can do to keep my worthy book to live but need to sacrifice the mobility of which I need to operate it with charger every single time. Or else I will need to dissemble and charge on my wife's book.
Last few days, I got a 3 beeps which I can confirm that it was a bad memory caused the issue. Tried reinsert and clean but to no avail.
I still loves the MBP but then it will cause more than bucks to restore, ie: new ram, maybe new motherboard? idk
Your support is much appreciated on this.