Try resetting your T.V or use any of your mobile as remote and check.
Batteries? I mean. Sounds dumb, maybe it is. Mine today was frustrating as hell because I changed them 2 weeks ago. Until a number of reboots and finally got a pop-up saying "remote batteries critically low". Pulled them. Checked with tester. Yup critical. WTF! ... ... Oh, my 5 year old plays with the remote CONSTANTLY. The remote has a motion sensor. 2 weeks dead. I used rechargeables this time so in 2 weeks I can flip and not add more trash.
You can still change the input in the upper right of the screen until you can find a better fix.
Had somewhat similar similar issue for which I called sony customer service. I tried their way and it did work. Here it is: Take the batteries out of the remote. Now place them back while pressing the power on button.
I hope this helps.
Use an Android TV app until you get it sorted out. Looks like your remote is FUBAR.
If the remote Is Bluetooth must be batteries, if Is IR maybe is sending the wrong codes....
I had this happen before on a top of the line Sony TV. I believe it's an Android problem. Have you done a hard reboot? Turning the TV off doesn't really turn it off. You have to either hold the power down a long time, reboot in settings or turn the TV off and unplug it.
If that doesn't work go to settings and then apps. Clear data in an app that you would think would be in relation in changing input.