Do you have a different TV you can test it on? This might confirm a bad HDMI connection, or at least confirm a failed device. You might also try a different HDMI cable. They can and do fail for no reason sometimes.
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I have a streaming stick and an Express. The Express has worked fine until this morning, when the remote stopped working. Tried the phone app, and that worked briefly until I decided to try a reset. Now I get a weak white blinking light or nothing, and my phone app says it can find the Express. So neither the remote nor the Express seems to be working.
Sorry, correction to previous message. Sloppy typing. My phone app said it COULDN'T (not CAN) find a device until I swapped the stick onto the TV where the Express had been. Then, finding and typing in the IP of the stick, the app finally found the device. Can't do that with the Express because I can't get into it to go to About and find its IP number.