Mac mini does not finish booting up

I have rebooted a number of times and the boot process hangs when it has almost finished booting up. Using my other Mac, I can see the Mac mini is on the network and I can log in to the mini remotely and see the files but the mini is not completely booted up. I have unplugged, started up with option key and selected a bootable USB drive and the mini still hangs when the process bar gets almost to the end. I have put the mini in target mode and used disk utility and first aid to repair the drive. When I restart the mini it still hangs. I have used option, command R to to get install files from Apple and after it downloaded files and started the install it still hangs at the end of the process. I have a 2011 Mac mini and was running 10.13.6. The install USB is 10.13