Again, it was not clear to me what happens when you do a Reset while NOT connected to the computer. Thanks for the clarification on your last post... This is an exercise in problem-solving, not reading comprehension (or mind-reading). 🙂
If nothing happens when you do a Reset while the iPod is not connected to power, that may indicate the iPod's battery is worn out and not holding a charge. Therefore, the iPod does not turn on at all while disconnected. A dead battery can also cause the iPod to not start up, even when connected to power. Or it may be a problem on the iPod's Lightning connector that does not establish a power connection (so the iPod's does not receive power to operate and charge its battery).
Another possibility is a faulty USB docking cable. To rule out faulty cable as the cause, try a different cable. Or use the current cable with a different Apple device to confirm it works properly.
You should also do what I described in my previous post about Disk Mode (even if you can't put it into Disk Mode)
Shut down (power off) the computer and disconnect all USB devices. You can leave standard USB keyboard/mouse connected, if used. If your computer is a laptop, connect its power adapter so that it's not running on battery power. Then, start up computer, run iTunes, and connect iPod to a direct USB port on the computer, by itself.
If you have a lot of USB devices connected at the same time, the total power draw may exceed the available power on the USB bus (so the iPod receives insufficient power). Connecting the iPod to a direct USB port by itself is a test to rule out that possibility.
Otherwise, you are limited in what you can do for troubleshooting, if the iPod does not turn ON at all.