How to hard reset 4th generation 4K 32GB AppleTV?

If unplugging the device and plugging it back in did nothing, then make sure the HDMI cable is working, try a different one, try connecting the Apple TV to a different TV.

If after all that, it still won't work, then you may need to contact Apple support and take it in for service: Contact - Official Apple Support

Did you bother to read the advice letter??

how do I restore a appletv that has a blinking led

https://support.apple.com/en-us/HT202118

Unplug it from power, wait 10 seconds and plug it in again.

My apologies, the 4K if it will not Restart (for whatever reasons) must be taken to your local Apple Store or AASP.