Thank you all - Yes that web page was what I was following
acording to that web page S905X does not need a device tree. "S905X: You can leave a tree that is already present on SD card"
I'll try a 2G one and see if that works.
I try gxl_p212_2g.dtb and gxl_p212_2g_nand.dtb and gxl_p212_2g_slowemmc.dtb but same - Stops at mecool banner.
I must be doing something stupid as others have got it to work.
Sucess, I used This and it booted first time. Few things dont work (keyboard/mouse) but at least it boot - and I know this is alpha.
Ok. now i see where I was going wrong. I didn't rename gxl_p212_2g.dtb to dtb.img (it was not ovious from the install instructions). Now it is working properly even keyboard/mouse & wifi works.