Might not need an SMC update. First go to the apple logo, about this mac and then to system profiler, an then to the power tab on the left side. Now make sure your battery is already pluged into the computer and check to see what it says. Does it say the battery condition is good? Does it say thats its plugged in and charging? Whats the cycle count? And also did you buy a decent quality battery or the cheapest piece of crap you could find? I had this issue on another computer where the battery was in, wouldnt charge, got it to charge once then wouldnt charge ever again.
Hope this helps and your answers could help me fix your issue!