XPERIA E bootloop after turning wifi on topic

i have big problem with xperia e (single sim, jelly bean 4.1 stock)
it restarts into bootloop mode everytime i try to turn on wifi on and i have to flash it with flashtool to make phone working but with no wifi
how to make this wifi working
will it work if i try to flash 4.0.4 firmware from e dula? or i will brick it maybe?
any ideas?