New laptop doesn't start

Three months ago I bought a brandnew Laptop (Asus) with Windows 8.1 and worked away without a problem.

Last night my AV-program (avast) told me that something's wrong in my boot-up and that the malware (whatever it was) has been stopped. And if I want to get my whole boot-up checked.

Sure I wanted it. So avast checked the computer asked afterwards what to do, I clicked "repair automatically" or something in that regard and the laptop restarted.

I worked away, everything was fine, at night I switched the thing off and this morning when I pressed the start button - nothing. Not one beep, dark screen, nada.

I tried several times, but still nothing.

Has anyone an idea what happened or if there is a trick to start the bloody laptop?