More info, but not yet the video that shows what pins.

No. That's how to do it when the bootloader works. My memory is slowly coming back, there's 2 pins on the back you need to short. But what pins I don't know. Let me open one and see if I remember more...

I send them a mail to ask. Will let you know when I hear something, also asked someone who also got the video. This happened a lot to me when testing tons of images for these boards. But haven't been doing that lately, time to start again.

Perhaps this one? https://www.youtube.com/watch?v=yhZahmbb03Q

Hi. Forgive me for my memory is very bad. There is a video somewhere on how to unbrick mekotronics Rockchip devices. I've been searching for it the last half hour but can't find it. I know I've got it on my pc somewhere. Email mekotronics and they'll give you a link to it. If I find it I'll share it.