i have a inspiron 3521 just came back from the tech support because of a Audio problem ... they said they changed the motherboard and the speakers

now when i connect my AC adapter while the battery is connected the AC adapter light goes off (no power)

to make it work while battery is in (to charge it) i have to remove the battery ,start the laptop and insert it while its running otherwise the AC adapter will

turn off

i need help what should i do?