First time installation. Endless loop booting

Hi.
First-time, excited user on hassio.
I tried to install to my Raspberry Pi 3B+ w/PoE.
Followed the instructions in https://www.home-assistant.io/hassio/installation/
I downloaded the recommended 32 bits version.
When I start the Pi it loops forever around
Failed (1)
Saving environment to MMC… Writing to MMC(0)… Warning at drivers/mmc/bcm2835_sdhost.c:400/bcm2835_send_command()!

I tried the full procdure 3 times, in case there was some error downloading/flashing, with the same result.
Help, please?

Solved! It was an SD card problem, Etcher verified the card, but still there was something wrong with it.
Kingston cards are out! SanDisk is fine.