AXP209 doesnt power on CB1

[ashkanHGT]

Hi there

I'm using cubieboard1 for my project. After several tests, some of our cubieboard didn't turn on again. I figured out the problem is AXP209 which has to Enable regulators(TCS4199 & TCS2109) doesn't work properly. I pulled up enable pins on TCS4199 & TCS2109 and the board turned on.

My question is what is the problem and what is the cause of this issue?
What can i do to prevent this problem again? 

[allen]

How many the board broke ?  How much  proportion of broken boards ?