display not seen while pressing power button phone is continuously off.

I have Blackberry Z10. Suddenly i took it from my pocket and was trying to make call, for that i unlock the phone. while pressing the power button the display didn't seen. only red led continuously on for three to four minutes and then LED gets off. I thought that may be battery got discharged so put the phone on charging.

Again pressing the power button same sequence described above is observed.

Can anybody have idea what is the problem and how should i fix?