Can you stop u-boot and type this commands (one line at a time) in it's prompt and post the result? Seems strange that your box needs som-v15 dtb.
This is what I got
CodeCuBox-i U-Boot > gpio input 105 gpio: pin 105 (gpio 105) value is 0 CuBox-i U-Boot > gpio input 68 gpio: pin 68 (gpio 68) value is 1 CuBox-i U-Boot > gpio input 40 gpio: pin 40 (gpio 40) value is 1 CuBox-i U-Boot > gpio input 160 gpio: pin 160 (gpio 160) value is 0 CuBox-i U-Boot > gpio input 164 gpio: pin 164 (gpio 164) value is 0
The output for "gpio input 160" is different: gpio: pin 160 (gpio 160) value is 1
The Cubox-i that I have is from (probably) the first batch. I pre-ordered it (September 2013), and it was delivered in January 2014.