The screen keeps flashing rear chk and the rear speakers are not making any sound.

I had the very same problem, and found that if you power up the receiver in DVD/CD mode, or tap the function button to display DVD/CB mode, the Wireless Rear Speaker AMP will automatically recognize and turn on the sound. This work around was not posted anywhere in the manual, just 1 of many workarounds I have had to put up with this system to work. Right now my fan went and it just keeps shutting down, I have had this system for about 15 months and very disappointed with the quality. My DVD player stopped working a few months ago, so now the system is rendered useless, not even sure it is worth fixing at this point since it is no longer under warrenty.