I had send a Marantz SR6004 Amplifier to your shop yesterday afternoon (10/4/11). Customer service bill: 0963. My problem is the power LED keep blinking twice every second. One of the technical staff has remind me abt the system might need to be RESET in order to turn on the system again. Hence I had searching ard from internet and find this may usefull and no harm for you to try before sent to Marantz HQ to troubleshoot. If you had done it perfectly please do give me a call to collect back the unit, 0123769859. Please refer to the detail stated below to reset the Marantz. Thank you.

"to turn on , press and hold down surround mode,exit and clear buttons for more then 3 seconds,system should reset. if it goes back to a flashing power light you will have shorted output transistors inside your receiver."