AM3352: AM3352 : the uboot-spl cannot boot up sucessfully

Part Number: AM3352

Tool/software:

Hi  

     the product cannot start U-boot SPL normally ,  one unit can send u-boot-spl.bin through xmodem successfully , but failed to boot ,  the console show nothing . Do you know what are the possible causes of this problem?

Have try many times , but always failed.  But it's ok with ohter units .

Xmodem :

   

U-Boot SPL boot :