Won't boot up, only vibrates

Hey guys real quick because this is the first time I have run into this issue. So I've done an uncountable number of iPhones and normally, as you know with how easy they are, it goes very smoothly and without any problems. So I did a screen replacement on this 4S and after the replacement the phone only vibrates and the backlight basically flashes and then turns off and continues to vibrate until I either unplug the battery or take it off the charger. The vibration goes in twos so basically a "buzz buzz......buzz buzz.....". I know this means theirs a short somewhere with flex cables but I can't pin point it at all. I've tried doing a number of things one of which being disconnecting each individual flex from its port and re seating it. I've also tried disconnecting one at a time to see if it's a specific cable that is shorting it out. So for example I'll unplug the power flex, re seat the battery, turn on the device, and see if it works. So far it continually does the same vibrating. I have done this with every flex including the digitizer and LCD. I did take a look at the board and nothing has been damaged as far as ports or components on the board itself. I just can't figure this out maybe it's right in front of me and I'm over thinking it. Regardless some feedback would be great from other who have experience with this issue. I would greatly appreciate it. Thanks!