Long story short, I tried to clean install. Activated erase the Macintosh HD, but it never finished due to forced shut down. (Please don't ask, idiot in family decided it was taking too long...). Opening Mac again in CMD+R, Macintosh HD was not inaccessible. I tried to recover what I could, but it was gone. Somehow I managed to change it into Apple Disk Image I think - one of the four "disks" that appears when entering CMD+R and going to Disk Utility. (Now I had two Apple Disk Images or whatever its exact name was) So that was not right way, I partitioned APPLE HDD and made new Macintosh HD, but that seemed to be empty. Now I decided it was safest to just call a technician and had him install El Capitan back on and not let anyone else meddle with it. So my question is as follows: does this sound like clean install was done? If there was (doubt it, but just in case) malware or trojan installed, was it wiped out and system is now clean?