Hello, my friend just bought this car and the control unit has nav and XM. The radio itself appears to be working from what i can tell but it will not produce any sound through any input(MB seems to be notorious for having no sound problems). I am able to navigate through the menus on the radio but that about it. Apparently the person he bought the car from had the car checked out at a local MB dealer and this is what they said under the estimate BODY ELECT CONCERN: "Right front can blocks and connectors are corroded. No sound from command" I found that i believe the dealership is talking about the Telematic CAN A located in the passenger side doorsill. I will verify if there is actually corrosion or not. He does not want to pay the dealer $1500 to repair this problem for it most likely to happen again, and would rather go aftermarket if possible. I have been reading a ton of horror stories about people with bad command units, bad logic 7 amps, bad audio gateways, and also damaged fiber optic cables and troubleshooting without the proper MB equipment may prove to be some where tedious. Am i able to skip the repairing part and jump right into installing a JL audio Fix-86 integration module and aftermarket 6 channel amplifier? I unplugged the oem amp in the trunk and started the car up and the radio functioned exactly as it did when the amp was plugged in. I quickly checked to make sure there was power at the amp but that was all i had time to do. Any input is greatly appreciated