How do you restore 1st gen Apple TV

Do you actually have a 1st gen? I just noticed your profile says you have a 2nd Gen?

If it's the original (big aluminum box with hard drive)

There isn't a way to restore any other way like on later models and i'm not even sure the firmware would still be active, unplugging simply forces a reboot which isn't of use here. As I said it may very well be a hardware issue anyway, the device is 10 years old after all.

If it's a 2nd gen (small black box)

You can try a restore via iTunes. Note: That model is also quite old (2010) and also considered obsolete, so not sure if the firmware is active there either

https://support.apple.com/en-ca/HT203028

you can see the difference between the 1g and later generations here

http://www.digitaltrends.com/wp-content/uploads/2013/04/apple-tv-1st-2nd-3rd-gen eration.jpg

when my 1g died it was the internal fan which stopped so it kept overheating and froze

You would need to go into settings and select restore. Bear in mind that any issue could be hardware related and the model is considered obsolete so it is no longer supported