8 
10 Trying to update it to windows 10 using boot camp
After the install finishes it flashes and doesn’t stop until I turn it off then back on then it says no bootable device please insert and press any key when usb drive with windows 7 on it is in please help
Did you try pressing the "option key" while trying to boot from your usb?
https://www.macworld.co.uk/how-to/mac/wh...
BTW, just so there is no confusion, the usb needs to be bootable and not just have a Windows 7 ISO (or whatever format) file copied to it. If the usb is not bootable, the computer won't boot even if you can try booting from the option key; you will receive the same error message as before.
prop man さんによる