If it's something that has started recently, there's probably a sticking button on the remote. I'm assuming it's a standard IR remote, and not one of the WiFi Direct versions. If there's no pairing button under the battery cover, it's the IR remote.
Look at the end of the remote though a digital camera, such as a camera on a phone. If you see a flashing light when you aren't pressing a button, that's the problem.
If there's no flashing light, or if it's a WiFi remote, it's possible (and likely) that the remote has failed. You're well out of warranty I assume (I don't know what TCL offers). But you can buy an inexpensive IR remote from Roku and other places for $20 or less.
You could also control the TV using the Roku app on a phone or tablet. The app is available for both iOS and Android devices. But it will only work if the phone and the TV are on the same network and there's no security feature blocking the phone from seeing other devices on the network.
Dan
Roku Community Streaming Expert
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