Help me figure something out....Please

[sturmj]

I have a Yamaha 5.1 receiver for home theater. While I was away someone hooked the rear channels up wrong, one speaker was connected to the two positive posts of the rear channels, the other to the two neg posts. Obviously they did not work in this configuration, and Im sure bad things are possible to happen.
Now the receiver is acting strange, the speaker that had the two positives does not play off its intended channel (rear left) but the speaker will play on another channel (say, rear right) so the speaker is good. Now for the strangeness (for me anyway) the speaker will play off the rear left channel when no other speakers are connected (only rear left channel connected) but as soon as the other speakers are connected it will not play.
So my questions are:
1) Since the channel plays fine (alone) the amp devices must still be good, not blown(?)
2) IF this is true there must be some other (easier ) fix for this (a resistor that biases the the two channels?)
where would I start looking or are these classic (or not so) symptoms of a blown channel?
I appreciate and help any one can give me.
thanks.

[ontoaba]

May be some cables swapped each other or something like that. Check it again or connect only two speaker first.