Windows 10 on a BSOD loop (totalled)

Please bear with me here, this is going to be a long one.

It begins about 4 days ago. Windows 10 updates, causing a HUGE amount of lag. I get worried, as my laptop is fairly powerful and it usually doesn't slow down. So I scan my pc using Malwarebytes, and get something like 67 threats. Even more suspicious, because I had Qihoo 360 AND adaware, in which in Qihoo I had all av engines enabled. I quarantine, delete all quarantined files and scan again using Hitman Pro (v3.7 I think) and AdwCleaner. After i restart the pc, suddenly in the login screen, my account is gone, and instead an other user and password tab appears. Here is my first query. This is not the first time i used the trio(MalwareBytes, Hitman and adwcleaner). I have used it before on mutiple occasions, and I remember the first time I did it, I somehow lost the pin on the login screen. I thankfully had a password too, and i signed it using that from then on. The second time I did it, I lost that too, and now I had to sign in using the microsoft account password that i had set online. So my query is, what am i doing wrong? is the trio messing something up? Or is it a virus?
I checked online for solutions and found users facing similar problems due to the recent Windows Updates.

So anyway now i cant do anything other than see the other user and password tab as it just doesn't accept anything i type in it. i cant safe boot cos there was no option of restart (or shutdown, there was nothing at all) on the power button. After a lot of problems, I was finally able to access advanced boot options. And I tried EVERY one of them, but none of them worked (even system restore failed). All of them showed an error but with no particular reason of not having worked. Being left with no other options, I reinstalled Windows ( I also installed Ubuntu in the meantime). Two points to note here. The first one being that grub never recognized Windows when i searched for it in the terminal. It showed Windows as FreeDos in the /dev/sdxx partition. The second point was that I installed the latest version of Windows that was available, so it came with all the updates that killed the last os. And this one was not clean either. The brightness keys were not working, so i had a lot of trouble with it. And secondly when i tried to install the drivers, some of the drivers(graphics being one) did not install at all, again with no reasons or with reasons i could not comprehend. I once again searched online for solutions and one of them said to roll back the monitor PnP driver. I did it. I restarted. BAM. BSOD loop. Well, alternately, cos once it would open startup repair, and once again none of the solutions worked. I used command prompt to check the disks, and it did resolve some errors, but not all, apparently. No good.

Now I have a lot of questions and I would like someone to help me with them.
Q1. Can someone give me ANY solution?
Q2. Apart from BSOD and startup repair, 80% of the times, Windows does not boot at all. When I try to boot , suddenly the purple screen of grub appears with some cuts ( like a partially loaded screen), and it just stays there. Explanation and solution please?
Q3. What is the reason all of this is happening? Is it a virus or is it Windows updates?

Sounds to me you could have a failing hard drive/SSD, and you're Windows installation/Linux could be easily getting corrupted.

Is the laptop still under warranty? If so, you may want to call tech support and send it in.