Unable to boot HiKey from sdcard after flashing AOSP

Hi,

I had my HiKey board booting from sdcard. I had HiKey Xen + Centos and these are the instructions: https://github.com/Jeeppler/xen-note/blob/master/arm64/hikey/hikey-xen-centos.md

Everything was fine. Then I flashed aosp on the HiKey with fastboot using these instructions: https://source.android.com/setup/devices#620hikey

Now in the boot time my board doesn’t see the sd card any more and boots directly to the android. Previously, I had these boot options in the boot time:

[1] fastboot
[2] boot from eMMC
[3] boot from SD card
[4] Shell
[5] Boot Manager
Start:

But now it jumps directly to Android without showing boot options.

Thanks,

For AOSP, it could only boot from eMMC. The SD boot is only for debian or other Linux system.