Does it not power up even if you remove and reinsert the battery?
If the phone won't power up at all, as opposed to not waking the screen, there is nothing you can do with an app - the OS has to be running for an app to work. In that case hardware repair is your only option.
If the phone is running but you can't wake the screen, an alternative lockscreen app that lets you wake the phone using other buttons might help (my old friend WidgetLocker has such options). You just need to not let the phone sleep until you have it installed and activated/set up. Reboot and keep it awake until done if this is your problem (pull the battery to force a reboot).