MBR Down A31S

hello i got a Q102 A31S tablet,

i flashed a wrong CWM .

i try to re flash it with firmwares for this model . i got 3 differents firmwares :

from livesuit all say " image file invalid"
from phoenixsuite " error 0x162 mbr down"

with phoenixcard, i can make a bootable microsd as "product" : the tablet boot with a red rectangle progress bar,
and stuck here,no progress, even if i wait 2 hours.

if i burn card as "startup" its boot from extsd and work,but with no intsd card mounted, 2go internal storage instead of 16go,
and apps/browser cant save downloaded content " no sdcard mounted"

i tried with FElix-master from github (windows version)

if i try to flash image or rewrite mbr with the command "ruby felix --mbr sunxi_mbr.fex"
i got a error , 'cant write new partition'

so i just wonder if the cause is the wrong CWM , or if my tablet is just dead ?
what can i do if programs cant rewrite partition ?

thanks if someone can give me any hint for a solution .