Unicorn Hat not lighting up at all

I just got my Unicorn Hat (PIM054) and installed it on a Raspberry Pi3B+. Everything on the pi is up to date. I ran several examples after the installation and nothing happens, none of the leds turn on at all on the UnicornHat. Examples run without errors.

Ran as sudo? I do believe for some strange reason you have to use sudo?
Firmly attached to the Pi’s GPIO?

Hi alfanumeric,
I am running the examples using sudo, checked the good attachment to the PI, still do not see any led lighting up.
Any ideas?

Nothing comes to mind? I have two Unicorn HD’s and an HD Mini. I get error messages if for example SPI isn’t enabled. Or I’m missing a required font etc. I have yet to get no LED’s lit without some kind of error message as a hint to what’s wrong.
Anything else attached to that Pi? If you have ever had other things attached and installed software for them, I recommend starting over with a clean PiOS image.

Thanks alphanumeric. I have rebooted the PI with a clean OS without luck but I have found a quick workaround. I have downgraded the piOS from the latest to a previous 2020 release: https://downloads.raspberrypi.org/raspbian/images/raspbian-2020-02-14/
and the unicorn Hat is now working as expected.

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Nice to hear you found a solution. I have resorted to older builds in the past to confirm something in the latest and greatest broke something that worked before.
My Unicorn Hat HD’s work OK in the latest 2020-12-02. I don’t think I’ve tried my Unicorn Mini’s with that build yet though?

I had a similar problem where only two lights would light up - on (a fresh install of) the default raspbian package available today in the Raspberry Pi Imager. I installed the light version of the raspbian from 2020-02-14 linked by oeolartep and now it works fine. That said, I also said “NO” to the install script for unicorn hat making changes to my audio, as I was also previously getting no audio out of my headphone out. Now, both the unicorn hat and audio out are working (haven’t tried simultaneously - guessing that won’t work)!

I suspect GPIO 18 may be used for i2s. I would think saying yes or no would have no effect on the onboard HDMI or jack out audio. Might mess up a hat with a DAC on it though. Just my best guess really.