Hello. My name is***** to JustAnswer. I'm reviewing your question now, and will post back with your reply momentarily.
When you start the mac, please hold the left shift key to try and boot into safe mode. Let me know the results.
I understand. When you get it to boot up, as SOON as it boots up hold down left shift key. What happens?
When you first start it again, and only hold down option, what happens?
Also, do you have another mac and an 8gb usb drive?
Can you tell me the model of mac it is?
What do you see if you hold down just the option key when starting the mac?
Perfect. Now plug in the usb, power on and hold option. What do you see?
Then we need a usb that is formatted the way we need. What usb did you use?
If you have come this far, this will seem repetitious, but it is what we need to get the usb to boot. It needs to be done
from your other mac. Not your windows.
Note that whichever method you use, you need a hard drive or thumb drive (USB stick) at least 5GB in size (an 8GB flash drive works well), and it must be formatted with a GUID Partition Table.
Please follow this article to create the drive so we can repair your other mac.
These issues often take time. I wont leave you until we come to a final resolution for you either way.
If you are satisfied with the help I have provided, please remember to click and submit a 5 star rating on this page. Your feedback is important as it is the only way I am credited for assisting you. Thank you.~Franklin
Also, i wanted to let you know, you can purchase this for 15 on amazon fully loaded and ready.
That is quite a bit of work.
Did you want to create it or purchase it?
The only way it wouldnt see your usb is if it isnt formatted properly, or the hard drive needs to be replaced.
Once you create or buy the usb, then you update this ticket if you need help installing. (sounds like you already
know exactly how to do that though. You are no novice).