Unable to start up MacBook

My MacBook suddenly won’t start today. It’s been turned off for a couple of days over the holidays. When I connect the charger, the MagSafe light is green. It’s been plugged in a bit over an hour but the green light indicating battery charge is still blinking at one.

I’ve attempted to reset SMC and PRAM by pressing shift, option, control and power button and power and command, option, p and r. In addition, I’ve opened it up and unplugged the battery cord and pressed the power button for 30 seconds before reconnecting the battery, the power supply and pressing the power button. I’ve also removed the RAM and inserted it again (as it looked like it wasn’t clicked into place)

Im unable to turn the computer off once the MagSafe is connected. It automatically turns on and the white sleeping light begins flashing. I can see that the fans are working and that there is a starting noise coming from the harddrive.

Here is some additional information:

• I replaced the RAM myself a couple of years ago (Kingston)
• the motherboard was replaced last year by Apple (due to the fault with this model)
• I don’t think the battery has been replaced and I know that it has said that it should replaced soon..

Any ideas what this could be? Problems with my hard drive, RAM, battery or something else?