Booting issue of Pogoplug Series 4

[jiuns]

Hello~

I installed the alarm on 8GB flash memory which attached on top side (USB 2.0).
After reboot, I can access the pogoplug by ssh.
Everything looks OK.

Then, power off the pogo and plug in the Seagate USB HDD(2TB) to USB 3.0 port for data partition.
When I power on, front light continue to blink and I can't access the pogo by ssh.

How can I use the 8GB flash memory(for rootfs) and 2TB USB HDD(for data) at the same time?