My laptop only writes in capitol letters, blocking my iD access to sign in

As a workaround, you can try holding the shift key for each character you want to be lower case–as in a reverse shifting. If that works, at least you can sign in but to permanently correct the problem you may have a hardware issue. If you have one, try connecting an external keyboard and see if it also only types in capital letters. If it does, your keyboard is probably fine and it’s another problem. If that corrects the problem, the keyboard likely needs service.

You might try cleaning your keyboard in case something is interfering with the shift or caps lock key. How to clean the keyboard of your MacBook or MacBook Pro - Apple Support

Also, you may check this article and its solution: MacBook only writes uppercase - Apple Community

One person in that last article also mentioned pressing fn+ctrl+left shift+F1. A few people replied and said that worked for them; however, I can’t seem to find any information about that sequence or why it would work.

I hope this helps.

Are you sure CapsLock is off?