Charging problems

Ok so a couple days ago I got a new lcd screen for my laptop -dell latitude e6420- and everything was going fine I got done fixing the screen and I went to power it on but I found out the battery was dead so I put it on the charger but the charging indicator went on for maybe 1 or 2 seconds so I left it to charge for a couple hours and went to turn it on it would power on for 7-9 seconds and without booting it just turned off then I unplugged the charger and plugged it back in then the charging indicator started blinking white it was a steady 1/2 of a second and I thaught it must be the the charger or the battery but I need some more ideas of what the problem could be