It may take a Startup Repair several tries to fix certain problems on your system.
But some folks have taken drastic action to get out of the repair loop. I would not suggest doing some of them, but there may be some commands you could try if you can get into a Command Prompt window, such as bcdboot and bootrec, which must be run from the Recovery Environment.
bcdboot C:\Windows
bootrec /FixMBR
bootrec /FixBoot
You might try taking the battery out and running without it, or take it out and leave it overnight.
Have you, or Windows Update installed any device drivers recently?
And make sure none of the normal F keys. like F8, which may need to be actively tapped during boot. If you could get into Safe Mode, you might be able to work things out.