I blew a breaker and now I can't get my Onkyo TX-SR601, how do I reset

There is a Onkyo recall or service program being offered. I'm not sure if your unit is included, but here is a site to check the serial number to see if it's qualified:

https://repair.onkyousa.com/na

This is posting on the AVS Forum board :
http://www.avsforum.com/forum/90-receivers-amps-processors/1652514-onkyo-acknowledges-failed-units-extending-warrranties-until-2018-a.html

C7524 = 0.1F

Onkyo 3000120 or FMC0H104Z

The problem could be bad solder connections on the main, or the audio outputs are breaking down when they get hot.

I had the same problem with my TX-SR601 receiver.
Solution: I changed the capacitor C766 (100uF/6,3V) on the "DSP and main microprocessor" or "U1" board. This capacitor is responsible to keep the settings in the memory. It is directly next to the SRAM ICs (Q705-706) (type: CY7C1019BV/CV33-15VCT).
Now the receiver works properly again.

Page 77:

"Not available in Zone 2 mode" Setting not allowed because the Zone 2 mode is turned on.

"Zone 2 is not On" Will not work because the Zone 2 has not been turned on.

TURN ZONE 2 ON.

Register and download the manual for free at retrevo.com

http://www.retrevo.com/support/Onkyo-TX-SR601-Receivers-manual/id/365ag212/t/2/

Page 55 shows the prerequisite settings for using the surround back terminals for Zone 2.

Page 60 describes USING Zone 2 and points out that only analog sources can be used with Zone 2. Are you trying to use digital sources? Read the notes regarding REC OUT.

It will work with any Line Level input. The Front Panel Video 4 Input looks convenient.

Hold Video 1 and Press the power button then turn it back on i had the same problem

Enter the menu for speaker levels, and increase the center channel.

Add another power amp to line outs from your main amp to your speakers this will give more power(current) to your main speakers as you have decreased load on main amp

Hi ripper

The unit has a built in display dimmer, with a button to control the level of brightness from the display both on the remote, and the front panel.Try this

regards
Graeme