Macbook Pro 2011 battery not charging error code

My Macbook Pro just turned 1 year old and the battery might be defective or dead ( Warranty just passed by ) it originally cam with Snow Leopard but I WEB upgraded to Lion (which was far from being easy ... had alot of crashes and hanging happening)

I have the now infamous battery not charging problem. The OSX status bar shows the battery icon with a 'X' meaning no battery. I think the MacBook is not charging the battery because OSX doesn't see a battery.

Today I just noticed that (IMPORTANT) with the power adapter connected, pressing the battery power level button displays a 5 blinks code. Otherwise with power adaptor not connected, the battery seems even too weak to light up even a single LED".

Even though I do a proper shutdown, it is to note that the MacBook Pro starts right away when I plug the power adaptor. I starts right away without me even pressing the power button.

Yerterday I really though the MacBook Pro was not going to work anymore, it kept abruptly shuting down again and again. I couldn't do any of the work I was supposed to.

I did PRAM and SMC resets and eventually I was able to startup the MacBook Pro and do some work but the battery still remains unavailable.

I have 2 of the same 85 Watt charger ( the first one being from a previous MacBook Pro 2008 --- which is waiting to get a repair ) and both performs the same: not charging.

Maybe the battery discharged beyond the point it can be seen my the MacBook Pro and OSX. Just like car battery, if it get discharges way too much, you won't even see the nominal voltage on the terminals even without any load.

EDIT: just noticed that even though it looks like no battery OSX reports that power source IS BATTERY (in the OSX status top bar )