It won't stay awake.

Performed a Ifixit 2015 MacBook battery replacement. After install, recharged using 5w charger as recommended. Mac would not turn on. Unplugged charger, then reconnected, screen lit up, showed charged at 100%, then immediately went dark. Will not light up again until you recycle (unplug then plug in) charger. (infinitely) Otherwise, it is completely black, no sounds, no lights. During brief illumination (3-4 seconds) curser will not move, keys have no effect. Any ideas?