iPhone 3GS no signal

hey guys
problem #1
have iphone 3gs 32gb, working fine screen got cracked... got screen replaced , since no longer have reception/no signal.
i've opened phone , checked connections connected , were.
sim in phone goes 1 bar searching no signal , keeps doing that. once text msg came through cant ring out.
have checked wifi , works, connects home modem fine , can surf web fine.
wondering if else had problem , how fix it. have new battery coming new antenna , new wifi antenna part coming..
if there else can reccommend me trying before replace parts great.

problem#2
since screen replaced.. (only glass not lcd)
have had restore few times.
playing angry birds , after 10 min or of playing screen goes zig zagy , have restore phone again or put on charger base , restart fine.. full bettery.

ideas , should fix this.

phone isnt jailbroken 3 mobile , unlocked @ end of contract

thank in advance
thank you.

 

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