Diagnosis
Signal interference or a depleted remote battery. The RJO101 uses Security+ 2.0 rolling code. Nearby LED lights or routers can jam the signal.
How to Fix It
First, replace the battery in your remote. Use a fresh CR2032. Reprogram it: press the black 'Learn' button on motor unit, then press and hold the remote button until the opener light blinks.
If That Didn't Work
You have local RF interference. Unplug any new LED garage light fixtures or smart plugs. Test the remote with opener plugged in but those devices off. If it works, you need a filter for the light.
Heads Up
Do not hold the remote against your head to extend range. That's a myth for older models. It does nothing for the 315 MHz signal this uses.