Maybe you done something wrong, open up again and check if cables are well distributed and not wrecked anything, my tablet was like this, led was fine, tho for a little wreck in the cable when I tried to close and did it wrong, it screwed it up. (also with a phone I had, which doesn't turn on anymore when I tried to fix this same issue, on it).
You must be very careful and check twice if everything is fine. Tho as I said, if bootabimation and charger mode are normal, must be something on system.
Enviado de meu LG-E975 usando Tapatalk
Don't get me wrong, but I'm really offensive when I get offended with something.
Former SMARTPhones: Nokia E61, Moto Q, HTC P4351, Nokia N85, Moto Dext/Cliq(Morrison/MB200), Moto Atrix (Olympus/MB860), Sony Xperia S(Nozomi/LT26i), Samsung Galaxy S Advance(SII Lite/ i9070).