iMac won’t restart or load up
My iMac has been slow and faulty for a while now so we recently got around to resetting it and wiping the software completely. I placed all my necessary files onto a USB and went onto recovery mode by restarting and using Command + R until the apple logo appeared. I then tried every option available to me , restored my Drive to factory settings and used the first aid kit on it to ensure it was all clear. Everything went well yet when i tried to restart with the startup disk , it froze at the end of the loading bar. After a couple of days leaving it there nothing happened , so we tried again and again , and were unable to download MacOS High Sierra nor could we use time machine. I cannot access my computer at all currently. Does anyone have suggestions as to how I can resolve this? It’s an older generation of iMac, if that helps with anything.
iMac 21.5″, macOS 10.13