Canvas 4 mobile not switching on after cracked screen replacement

Hi,

I replaced my cracked touch screen of my Micromax Canvas 4 A210 from a local service centre, now it is not booting.

I went to the same guy, he opened the phone. When he disconnected all the connectors to the main PCB board and powered with an electronic multimeter & battery booster, it got booted and we could see increase in the current readings.

So, he thought there might be some loose connections. He connected everything and blah..again it is not booting. He is saying it is due to problem in the power IC.

NOTE: THE main PCB is booting when disconnected and removed a little outside, but not working when it is connected and put in place properly as it should be.

I am not sure if that is the case. Any ideas, what could be the reason and how it can be repaired.

Obviously I'll get it repaired from the same guy, but I have to know the reason so that I can bargain properly. It was his mistake, right?