gpad 8.3 only boots into twrp, can't go into download mode

I had version v50020d, flashed twrp from the play store app I think. It's rooted. I did a factory reset and it got into twrp and never booted the system. I followed some tutorials for ota softbrick for g2 and some others and now it mounts data but everytime i reboot it, it seems to not mount system by default, so it boots into twrp. I wiped the system as some site told me and i think i messed it up. I flashed cm12 the september stable version. I seriously need your help. My gpads battery level is pretty low too. I really need to get it working again.