HTC S 710
System blanks out, hangs, shows no SIM

I purchased an HTC S710 Aug since then I have had to reformat and reload OS thrice and in July 08. the motherboard was replaced.

Recently problems have started once again

System suddenly blanks out, and I have remove battery to reset

Blue light (blue tooth) is continously blinking inspite blue-tooth being disabled

Repeatedly shows no SIM.

Each time I go to service center they just reformat, by which all data is lost, but no solution is in sight.

Now they say instrument it is out of warranty and hence they will charge. This is inspite of changing the motherboard 3 months back.