6230 unlocked but no signal

hi its my frist post please be kind.
i have just got a 6230 off ebay.
i had the phone unlocked, an it worked fine then the signal dropped to 1 bar an now it has nothing, i can access the menu but it will not find an operator.
sometimes it does get a signal but only in certain areas?
does this mean my antenna is broke or has it been barred.
if its been barred how would i go about sorting it out.
i have tried some codes using the imei number but got (code error) then (couldnt unlock code) or something like that. so i think i used up all my attempts.

well i have replaced the antenna and been into a nokia service centre an they confirmed the phone is not blacklisted anyone got any ideas, what could be the problem.
also if i had the phone unlocked then i tried again an used up all my attempts would that mean it has locked itself again.

didn't see where you were from but maybe the phone doesn't have 850 band so only works where 1900is available.

You could always try getting the pm file reflashed to the phone. This part of the software controls the phone connecting and registering to a network. I fixed quite a few phones with signal problems just by repairing or reflashing the pm file. Hope this helps.

Chris.

I have the same problem with a 6230i ,is the 6230 pm file the same as the 6230i model its just i have been searching for the 6230i pm file on all my support area's and there isn't one there is only 6230 :???:

Antenna switch....90%..next PA.........
WBR!
sergo_zmeia