Make sure if you ever try a different power supply that the important parts match each other:
Volts: 5V (unless it is an M6)
Current: Double check, but if it is a decent 2A (or more) supply, you'll be fine normally
Polarity: Check whether -/+ are on the inner prong
Finally, sounds obvious, but make sure they're the same size, if you break off the pin/prong your device won't work again.
If the device is from us and purchased within 12 months, we'll help you restore it, repair it in our office, or if those aren't possible, replace it.
Send us an e-mail -
[email protected] with the info mentioned here -
http://www.droidboxforums.com/threads/what-to-include-if-you-need-to-e-mail-us.364/
I'm not trying to tell you NOT to buy a new device, just that we'll hopefully get your current one up and running. If you've got a 4K TV, it makes sense to look into more recent models, or if you've got other TVs in your house, you could start pairing them up with a DroidBOX each.