FF Won't Start

Hi:

LOL.
Too funny.

I was merely trying to assist you with restoring your Firefox to working order, along with providing some friendly suggestions about how to mitigate the effects of a potential data loss in your browser profile due to power outage or other catastrophe.
Bookmarks are -- for most users -- an important part of the browser profile and would be the hardest piece to recreate from scratch.
Perhaps that's not the case for you.

When the conversation switched mid-stream to backing up/restoring email folders, that was jarring.
And it could be confusing to a casual reader of this thread about Firefox -- a basic computer user might wrongly assume that one's emails are somehow stored in one's browser profile.

I regret having wasted your time.
In any event, I'm glad you were able to resolve your issue.
I hope that your browser profile, emails and all your other data will be safe from loss, through backup/imaging strategies, an uninterruptible power supply, syncing to the cloud, and/or other means.

Take care,

MM

Just some suggestions.

Loosing power seldom does harm. Your computer looses power every time you shut it down and turn off the power to it. It's the restart after a power loss that causes the damage.
If one is with the computer when the power goes out just unplug the computer and wait for the power to come back on and be steady, and then plug things in and boot.
Some times when the power comes back on you will have a few power on/power off/power on flickers, these can cause damage if the computer is set to start after power loss.

Check your bios. Some will have a setting for what the computer should do after power loss.
Select do nothing not restart.You should do this manually after the power situation is over.