Help needed urgently my GT I5801 won't turn on
A few months ago my gt i5801 got a weird problem, whenever battery was low and I receieved a call, as soon as I hang up the call the pop up (power off, reboot, silent, data on/off) which normally appears by pressing power button pop ups and the phone enters in a boot loop it won't go past the gt-i5801 logo untill I remove the battery and restart it. I thought it was problem with the kisadworkx rom so changed to purumod rom but still same problem. It was all fine till 1 aug 2014 when I got a call my phone got into infinite bootloop, I went to samsung and few local shops but they were unable to fix, then I searched over internet and found that it maybe the power button problem, and someone on the galaxy y forum wrote that repeatedly pressing power may boot up the phone and it worked for me but after few seconds again the pop up appeared and again same bootloop. And and nothing works even if I enter cwm it switches off after 1 or 2 seconds. only download mode stays and I can flash rom easily but it won't boot.
please help me figure out the problem, this is my regular mobile.