Me and my friends have had quite a few times this month where we hit play on the battle.net launcher, and then our PC’s grind to a halt, the sound over discord sounds like you are disconnecting going robotic, the game NEVER launches, it’s missing from the task managers processes page, and to stop the problems we have to go over to the details page to end overwatches task from there, my overwatch is on my SSD and i have a relatively decent system, my friends are on both SSDs and normal hard disks and they use much better equipment than me say like 1080tis and ryzen 7 processors, we all run into the same problem and it always ends in NEEDING to scan and repair and this has only started since the overwatch halloween update.
Kind of a pain in the kiester but you should know that something is going wrong here, and it locks up the ENTIRE SYSTEM when it does, slowing all things to a crawl while it fails to launch. But whatever it is it came with the halloween update so you should have an idea of what you did to break the launching process this bad. Hope you get it fixed soon