replaced LCD screen, phone went dead. turned on several days later

So, I replaced my cracked lcd screen, which I have done plenty of times, and when I tried powering the phone on, it wouldn't. The battery was fully charged at the time. I replaced the new lcd screen and put the cracked one back again, still dead. I don't believe it was the new replacement screen since I connected the cracked screen and still had same problem. Anyways, Three days later I tried turning it on again and surprise! It works back again. Has anyone experienced this problem before? Or know what could have caused it?