Not able to wake the board from deep sleep(System off)

I am very new to Nordic products so please excuse my ignorance.I have been trying to put my nrf52840 board to deep sleep. It seems to go to sleep but when I try to wake it up by pushing the buttons, it doesn't wake up.

This is how  I modified Ble_app_blinky_c, I added sleep_mode_enter(){}, buttons_leds_init(){}, and bsp_event_handler(bsp_event_t event){} from Ble app template . And then I am calling buttons_leds_init  and sleep_mode_enter in Main.c.Basically I want the board to be in deep sleep at all times and wake up only when I push the buttons.

I have included my project below.

What I am doing wrong?

Thank you in advanceble_app_blinky_c.zip