Can't flash system.img in fastboot mode on KFHD 7" topic

Please help. I had Omni rom running fine. One day I turned on the tablet and got stuck in a bootloop. I tried to boot into twrp and it just sits there on the teamwin logo and wont go into twrp. I have factory cable and can get into fastboot, but the system.img will not write to the tablet. Here is what I get:

C:\>fastboot -i 0x1949 flash system system.img
target reported max download size of 1006632960 bytes
sending 'system' (907264 KB)...
OKAY [312.408s]
writing 'system'...
FAILED (remote: : Write partition)
finished. total time: 315.015s

Any help would be appreciated.