An unrecognized adapter is one of three things: The adapter is faulty (most likely a damaged plug or center pin, A damaged DC jack in the system. or A blown out charge circuit on the system board. Try a new OEM adapter first, replace the DC jack second -- and if neither of those gets the adapter recognized, it's the system board that's faulty.  
My Grandson has two inspirion 15 5570 computers that stay at different houses to avoid transporting.  Recently both have developed the identical issue.  1. The charging light flashes 3 amber and one white. (Manual states CMOS battery dead).  2. The battery does not charge. Battery health is o%. 3. I have replaced the battery and power cord in each and still have the same issue. 4. One suggestion was to update the Bios.  I have tried that and have been unsuccessful even with /forceit switch. Does anyone have anymore suggestions? Thank you in advance Grampa H 
Inspirion 15 5570 battery charging issues