galaxy grand 2 software problem

hi i just buy my galaxy grand 2 from a guy and i was surprised that this phone is a disaster
- i can't access the download mode
-the recovery mode showsa message :" no commund "
-when i opend the phone it sad " unfortunately the system UI has stopped "
-the wifi works only if the phone is 2 metres from the router and it show a message : "NVRAM WARNING: Err = 0x10 "
-the luminosity dont change even when i scroll
i don't know what to do really i can't flash a ROM or do nothing even when i unzip a rom it sad installation aborted
PS :
kernel version
3.4.5
root@huangyisong-desktop #2
sat Oct 11 16:21:50 CST 2014

but the phone don't have root access i checked :/
please i need help thanks ....