Is there another way to charge the device without using the DC port?

If the charger doesn't charge the speaker, but you know the charger works, then it'd likely be something obstructing the speaking from receiving charge. If you’re unsure of your charger maybe another one is handy to double check. Alot of speakers that are mass produced are not soldered structurally sound enough for too much wear and tear. Imagine a line of conductive metal that someone melts down and connects the battery to the metal port that serves as your, in most situations, only access of providing charge to your device.

My little sister had this happen to her several lime asking if I could fix it. If you can't charge the speaker through any factory inputs, open it and see if the solder is cracked. If so, maybe experiment and purchase a soldering iron from Walmart or online.

Disclaimer: If you have a valid warranty on said device, use it while you have it. If the problem is not the physical port, batt, charger, or connection from one another; then there is nonfunctional hardware or connection to and from one another.