J7 sky pro is not powering up and blinks on ND off where n plugged in


Hi I’m jayj new the high on Android and I got a problem with my galaxy SM-S727Vl j7 sky pro it seems to not hold a charge and when it’s plugged the battery lite just blinks off and on while vibrating I trying to hard reset it and it stays on to do that even in download mode it stays on what is the problem with thanks for the help