HomePod could not be powered on

Check that it is plugged into a live power source. If the HomePod's plug has a fuse check that hasn't blown. See If HomePod isn't responding - Apple Support.

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The .fuse might have tripped in the .breaker Box or Electrical Panel in your home. Did you test another appliance or lamp in this wall outlet, test the homepod in another outlet?

Does it light up at all ? If it lights up it’s powered on.

See if the touch was changed somehow, this will affect how it responds to touch

Use Touch Accommodations on HomePod

https://support.apple.com/en-ca/HT208433

You can try resetting HomePod,

the 5 second count (done twice) as instructed below is very important

Reset HomePod:

Press the top of HomePod to reset it

If you can’t remove HomePod from the Home app, you can press the top of HomePod to reset it to its factory settings. Here’s how:

1. Unplug HomePod, wait 5 seconds, then plug it back in.
2. Wait 5 seconds, then touch your finger to the top of HomePod and hold it there.
3. The white spinning light will turn red. Keep your finger down. 
4. Siri will say that your HomePod is about to reset. When you hear three beeps, you can lift your finger.

If you still see HomePod in the Home app after you reset it, then you'll need to manually remove it from the Home app.

If you’re able to reset it, then you’ll need to set it up again.

If the above steps don’t work, the only option is to take it to Apple and see if it can be repaired or replaced