The purple 3500 stick was introduced in 2014, and was replaced by the 3600 two years later. Your 3500 is getting kind of long in the tooth, so it could have gasped its last breath.
The fact that you didn't get anything when tried on a different TV does make it sound like the problem is with the 3500. Just to eliminate the TV as the culprit, have you tried your other working stick on this TV?
Roku Community Streaming Expert I am not a Roku employee, only a user like you. Streaming Stick 4K+ 3821 | Streaming Stick+ 3810 | TCL Roku TV 43S245/C107X | Streaming Stick 3600
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