Sherwood RX-4105 Receiver "6106" Questions

i am wanting to start using optical but the channel (01) keeps flashing and theres no sound? Any Ideas? CD 01 coaxial digital or optical inputs. If the 'o1' is flashing this means there is no signal. ...

can't get the subwoofer to work when the fronts are set LARGE? I can't get the subwoofer to work when the front speakers are set to large, if I set them on small, the subwoofer line-out works fine, ...

i have Sherwood rd-6106 amplifier and when i turn him on it goes back to standby after few seconds. can anyone help? after i tried to turn him on a few times a smoke came out of the device and he shut