I was ready to toss the spot--though it's one of my favorite Alexa devices. Driving me nuts, the screen flicker. Hard reset, moving to a new location, just couldn't fix it.
Before I tossed it, I thought I'd try the power supply for from the Echo Show I have in the Kitchen. Not expecting much, I plugged it in. And what do you know! No flickering, even at the brightest level! So the obvious take away is that the power supply or cable are bad. But I swapped the power supply with the Echo Show (hard to keep all the echo products straight), and it booted right up, no flickering. So everything is working, except I have a black power supply for the white spot, and a white (found out these two words together are banned--appropriately) power supply for the black Show