I got a "zap" sound from the phone & now it doesn't work

I got a "ping" sound & a then text. I replied to the text. Then another "ping" text sound, and then immediately after a "ZAP!" sound and the phone shut itself off and went black. I tried charging it, but the screen is totally black & unresponsive & now I can't even turn the phone on.

Any idea what this could be? How to fix it?