Retina MBP do not power up after sleeping for few days

I have a macbook retina 2012.

It was at 56% when i closed the lid, and then i had to leave the town on an emergency basis.

After I got back after a week, it didn't wake (which it should have), so i pressed the power button. Did not help.

I reset the SMC, the light did went from orange to green, but power did not come back.

I forced start it (took the power chord out, pressed the power button while keeping the power chord out for 10 seconds, put in the power chord)

The system did came to life, but it showed no battery found with fans working at full speed.

turned off the system, Reset the SMC again, but the system did not come to life.

It has been on power for around 3 hours now. What could have been wrong?

//mouse