MacBook Pro shut down, won't come back on!

I was working on my MBP model a1211 today, when it suddenly shut down by itself. I immediately thought low battery, so i plug in the charger. Charger light came on " green", but never changed to the " orange" charging mode. I checked the battery, it was ¾ fully charged! Why did my MBP shut down suddenly. Luckily, I was twice today, 3/23/2014, able to get the laptop started, just enough time to back up important work files, before it would shut itself down again. This happened three times today,now no more luck. MBP will not come back on, no chime, no hum, nothing! I'm guessing PRAM Battery, but IFIXIT is suggesting the " left I/O Board" Any idea would be appreciated!

RSRSPARKY

Well folks. I got my MBP working. First I replaced the " Left I/O Board", with some improvement, then I replaced the " PRAM" battery, which I manufactured myself. Snapped the generic main battery back in, and the MBP started right up, but then shut down after 10 minutes. Tried an older APPLE COMPUTER battery, only holds a two hour charge, haven't had a problem since! So, I figure my laptop must have suffered a surge during the previous evening, damaging the I/O board, PRAM battery , and the main Battery. A new MBP battery is on order, expected any day.

RSRSPARKY