Build AOSP for Hikey970

Hi,

I have a question about flashing the compiled AOSP into the board.

I flash the board with prebuilt image and binary files in the hikey970 blog. now I want to have a little change in the source code and compile the source code and flash it into the board.
1- which files are affected and I should flash them to the board?
2- when I flash just the system.img file, it is OK, but when I flash system.img and userdata.img and cache.img, the board will not boot. Do you know the reason?

Thanks,
Ehsan

@doitright answer:
" 1. The affected file(s) depends on what changes you made, and where. Generally speaking, changes could be contained within any of the following partitions; boot, dts, system, vendor. Does the 970 have a vendor partition? I don’t actually have a 970.
2. It is unlikely that anything in the cache partition could have a drastic effect, but if changing the userdata partition (effectively reformatting it) causes it to stop booting, then it sounds to me like there is an issue with first boot setup.

When you say it doesn’t boot, what do you mean? How far does it get? What have you done to debug it? Is anything spilling out the logcat?"

I encounter the same problem when i flash system.img and userdata.img. I checked and found out that sdd15 can not be mount to /data.You can try to use the following command to confirm that the problem is the same.
$su
#mount | grep sdd15
#mkfs.ext4 /dev/block/sdd15
#mount /dev/block/sdd15 /data