Minix U9-H not booting from SD card, first installation

Hi guys. I just received my Minix U9-H, I have prepared a SD card to install CoreElec.I followed the guide, step by step, letter by letter., but it will not boot from the SD card.

One thing though, the guide says “Turn off your Minix U9-H. Insert SD card, Plug power cord while pressing power button for several seconds until CoreELEC boot screen appears”. When I have my minix unplugged, I mount the SD card, push and hold the power button and then plug the power, nothing happens. But as soon as I release the power button the box starts. But at this point, I am not able to get it to boot from the SD card, the box is stuck on the MINIX start screen.

I take for granted that I am doing something wrong here, but what?

All input are of value for me now.

EDIT: Well, I found the guide here on CoreElec’s forum also, which differs on that part. " insert SD card, plug in power cord. Then hold in power button for at least 6 seconds or until CE Logo appears." With order words, do not unplug, press and hold power button and then plug the power.
Okay, so in that case, I have a faulty bootable SD-card ( Samsung Evo+ MC32GA microSDHC Class 10 UHS-I U1 32GB).

Any Suggestions on this?