phone battery died and goes on and off

my phone's battery died when i was walking outside and when i tried to turn it on with the power button it did nothing it didn't even showed me the dead battery sign.

When i got home i plugged it in the charger and waited for a bit, after some time it looked like it would turn on, the screen became white with a black apple logo in the middle, after 3 secondes it turned off again and then it turned on again. and repeat.

what do i need to do??

can anybody help me?