Question Dead Dell Latitude E5550


I have a Dell Latitude E5550 laptop that was working fine the last time we used it. The other nite we went to use it and it would not power on. I wasn't too surprised by that since it had been quite awhilè since it was last used, so I dug out the charger and plugged it in. It still wouldn't power on, so I suspected it needed 'some' battery charge and would be fine. Note that what I believe to be the battery charging lite at the front of the laptop did not come on. I let it charge for at least a few hours, and it was still dead. The battery was warm from charging. I removed the battery and charger, held the power button for 30 secs to dissipate any residual power, then connected the charger only and tried to success.
I have no clue what else to try. Tested voltage on charger and it is in spec.
Any suggestions would be appreciated