Flashing Mini6410 unreliable

Flashing the Mini6410 with a sd card seems to be very unreliable to me.
I tried it several times, refused the card over and over again, tried the
os= string in all combinations (with a leading space, "Android" or
"android") and so on.

Suddenly, it work. It switched the board off, and without touching
anything, it stopped working - no inital beep, nothing.

It just switched the board on and off several times, and it worked again
(?). 

Is there a way to make the flashing process reliable? I mean, I don't want
to power the board on and off 20 times to start the flashing process...

are you use a TF card? that's not a good way.

You must using a 4GByte or 8GByte SDHC Card memory.

I have the same problem. I can't start any OS from SD-Card. Led1 starts
blinking but os doesn't load.