android S5 mini No command !

[l_e_a_1]

My son was playing with the phone. He must have pressed the volume button along with the power button on the side. The screen is black with a android sign and a red exclamation on it and it says no command. What should I do now?
Please help

 

[Rukbat]

Hold the power button in until it restarts.

If it still doesn't work,you'll have to reflash the ROM. It sounds a lot more scary than it is. See [Samsung] How to flash Stock ROM via ODIN. (The only problem is that you'll lose all your pictures, music, any apps you've installed, etc. You get an "out of the box" phone. There's no way of replacing a corrupt ROM [if that's the problem] and keeping your data and apps.)

And teach your son that phones aren't toys.