Macbook pro boot/power issue

Hi Guys.

My mid 2012 macbook pro will not boot into the os unless i first remove the battery connector from the board, leave it a min and plug it back on (putting metal bottom on also) and plugging it in and starting it there. The Mac will then go for a certain amount of time before powering off. Is this a battery issue and will adding a new one solve my issue?

Thanks, MAJ.