HELP! Dead Nav/Radio with Hum

[md_sailor]

Please! Can anyone help? in the recent past my nav/radio went out for a few days and before I got to open up the dash it came back.. When it came back everything functioned correctly with the exception of my Ipod. It was dead. Now the Head unit is gone again and I have a faint hum through the small overhead speaker which is in the head liner aft of the OnStar Mic. the OnStar controls have power but there is no sound when they are activated. Does anyone have any thoughts? I have a 05 Nav unit with the USASpec Ipod adapter in place of the CD Changer and Sirius in place of the XM Factory unit. Any Help or thoughts would be appreciated.