I recently got my laptop back from my little brother, and it was running really slow. When I ran malware bytes, it had over 350 threats found. I removed them all and restarted the computer to find that I can no longer log on. When I turn it one sometimes it lets me type my password and it then says "welcome" with the loading circle forever. I tried a ton of things in safe mode and I can't get it to work. What should I do?