Because the RC-799M is from the "Pre-HDMI-CEC maturity" era, do not expect magic.
Insert two fresh batteries matching the positive (+) and negative (-) polarities marked inside the compartment.
The RC-799M remote control is natively compatible with several Onkyo AV receivers. It operates most essential functions right out of the box without any programming. It is the primary remote for the following models: TX-NR515AE HT-R758 HT-S6500
Look up the 5-digit remote control code for your device brand in the official Onkyo code repository.
The Onkyo RC-799M is a versatile factory-original remote control designed for a wide range of Onkyo Audio/Video (AV) receivers. If you have misplaced your original user manual or just bought a replacement remote, navigating the setup, programming, and button layouts can be challenging.
Press the RECEIVER button first. If you previously pressed TV or BD/DVD, the remote is sending commands to those devices instead of the Onkyo receiver.
Drop your device brand and model in the comments—I’ll help you search the full code library.
If successful, the indicator light flashes twice. If it fails, the light flashes once rapidly; restart from step 2. Method 2: Direct Receiver On-Screen Setup