Mboot for P75-628VX V6.0

bitcom

Hi everybody I own a noname 32 inch tv, based on this motherboard P75-628VX V6.0This board has 8GB nand and 1GB ram and the main chip is MSD6A628VX-ST.
I can use RT809H to flash boot but having trouble flashing mboot.
I downloaded "MS628_boot烧写" from this forum and flash by serial console but after finish, the board does not boot anymore and I have to reflash boot code again.
So I'm wondering if this older board "android 4.4" uses special mboot version.
Since this is a no name brand here in my country I can not go to manufacturer's web site and download "mstarupgrade.bin" to extract mboot.bin.
So my only hope is that somebody here can help me to get it.
Here is a picture of my board:
Thank you very much
I invested all my saving to buy this programmer and still can not fix tv.

技术支持008

here are two kinds of this chip, there are built-in and external DDR, different hardware is different boot page is different.

家电医生、阳光保险贾红民

能翻译成中文吗，我看不懂。谢谢。