Blue Power light is on but screen wont turn on

I recently started playing my 3ds again i had it put up for a while. some times it will start up just fine. but sometimes the blue power light comes on and thats it nothing pops up on the screens, no sounds, no nothing. Also I can press L+R+X+power button and it goes to the calibration screen and that sometimes allows me to get threw butsometimes that doesnt fix it. im thinking its a short somewhere but im not sure exactly where i should start at to diagnose the problem.