Onkyo TX-NR 838 Manual page 109

The registration is complete when the remote indicator flashes twice.
The remote indicator flashes once slowly when registering the remote
control code fails. Try the registration again.
Pressing any other button than a colored button cancels the remap
operation.
Resetting the REMOTE MODE Buttons
You can reset the remote control code registered in the REMOTE MODE
button to its default status. This operation can be executed on a single
REMOTE MODE button.
1. Press HOME for 3 or more seconds while holding down the REMOTE
MODE button you want to reset.
The remote indicator stays lit.
2. Within 30 seconds, press the REMOTE MODE button again.
Resetting is complete when the remote indicator flashes twice.
To reset all the remote controller settings: While holding down RCV,
press and hold down HOME until the remote indicator lights (about 3
seconds). Press RCV again within 30 seconds.