Sorry for kidnapping this thread, but I noticed that the thread starter has deleted his user account so he probably won't mind.
I have a similar problem with my SQ6 after a couple of years stand still. The car has been parked in my garage, with the electrical mains switch turned off, and unused for about 4-5 years now. When I tried to start it up again two weeks ago I got no control outputs at all, no spark, no signals to the injectors, not a single sign of any activity at all.
I tried to connect to the ECU using both DESCProW and EcuOffloadTool (through serial communication) but DESCProW reports "This program will only connect to Pectel External ECUs", and OffloadTool can't connect either.
The engine was running fine when I parked the car in my garage, and I'm still using the same old WinXP-laptop as I've always used before.
I'm using a USB->serial converter and if I try to connect to the ECU without turning the ignition on only the "transmit-LED" is blinking, but when I do the same with the ignition turned on I get a blink from the "receive-LED" occasionally, so there's some kind of activity in the ECU. It's the same USB->serial converter that I have always used when flashing the ECU before, I have also tried another converter with the same disapponting result.
I have checked that I have supply voltage to pin 49, and engine ground to pin 23 and 24. I hooked up the oscilloscope and checked that I have some sort of activity on the RS232-pins.
Any ideas what might have happened during the stand still? Is there for example an internal backup battery that might have run empty? Is there any way that I can revive the ECU myself in case of an empty backup battery?
Mats Gustafsson from Sweden