Fr external DVD drive, it may not be getting enough power, which kind is it ?
For phone, are you sure USB cable is data cable and not only for charging ?
Earphones with a mic in them come in several configurations, ones with separate mic and headphone connectors or with one connector with 4 contacts. they are not interchangeable. Laptop, does it have separate output/input for headphones ?
There's more to laptop battery than just battery. There are sensors for temperature and controller for charging, any of those misfires and there comes trouble. I usually test a laptop with and without battery just to troubleshoot that part.
What you described is definitive proof there's...