Need help , weird problem on downgrade
So long story short:
when i downgrade my phone to 4.2.2 , phone is not stable at all , it only works 20-30 seconds and then it restarts .
i tried both tot and kdz method , also did factory reset . but still same . phone only works on kitkat : official 24A/25A(newest firmware) , or some custom roms on kitkat . but JB doesn't work anymore .
some time ago it worked , but for now it doesn't .
So what should i do? i can't understand what's problem . should i try to do that on other computer or with other usb or whatever?
I need downgrade, because my cell radio is off on kitkat and i'm not getting signal at all , radio is disabled (can't figure out whats wrong with this)
maybe i have some hardware problem and it's not software?