LED on Pin 13 always blinking

I'm using ARDUINO UNO

I didn't connect anything to the board

The battery is a 12V Lithium-Ion (3x4.2V, 2000mAh cells)
Dimension 15.2x10.2x8.9 cm.

yes the voltage regulator is heating and it seems burned, I have attached pics of the regulator ,also in the regulator the output pin gives 1.79V and input to the regulator is 9.08V

the battery voltage is still ~12V when connected.