Unhappy Tablet Dicra TAB719

Hello, I've a Dicra Tab719. I had problems with wifi (unstable) so I installed cm10 but wifi stopped working completely and when the screen turned off for a few time it didn't turn on again and I had to force reboot :/
Now I reinstalled the original rom (not quite, i cannot find the original, i had to install the Tab710 stock rom instead), but the problems are still there.
So the problems are:
- wifi doesn't start. I switch wifi on but it doesn't start and it switch back off
- the screen, after a while that is on sleep, doesn't turn on

I'm mainly interested in the wifi problem, it's useless without a connection (it has no 3G module).
Any idea? Thanks in advance everybody!