help unlocking and imei changing with samsung n620...

i tried unlocking a n620 yesterday
well i unlocked it with UST 3.5
when i tried inserting a simcard from a different network
it got a system failure msg
and i tried that "repair system failure" option, didnt work...

1. therefore, im asking help from one of u guys who already did that before, what prog do i need ? , how to use it ?

2. again, im asking u guys who did this before, i mean imei changing now, how can i change the phone imei ?

3. is there a prog which can tell me if the com1/2 work ?
i need to know that my pc reckognize that the cable is connected to those ports..?

thanks a lot to all helpers