Tzumi speaker won’t keep playing while hooked to power

Tzumi media player won’t keep playing while hooked directly to power. The charging light doesn’t light up anymore. While hooked to power it will play for a little while and then say battery is dead and cut off. If I leave it hooked to power it will charge back up (without charging light) and play for a while till battery dies. Repeat. This is all while the speaker is hooked up to power