Looking at one of my other cars. It was flooded up to, from the ins. adjuster's marks, the floorboard. Only code I'm getting is 1636. No Ready light, no attempt to start. So, I've been reading through some posts here, and I read the diagnosis procedure in the manual, but I don't have a scope. Instead, I'm just thinking of buying a used ECM and ECU, swapping them in and seeing what happens. Or better, just swapping in those from my running car. Is that a fairly straightforward process? I.e., unplug, unbolt, replace, then let it sit with the key on for 30 minutes before trying to start? What are the chances that the HV battery would still be good after sitting for two years? Are those bad computers the reason I wouldn't be getting any battery-related or other codes?
If it was a BRAND NEW factory HV battery and installed shortly before the car died, I would say there's a good chance it still has enough charge. Speaking from experience on that. Brand new batteries are amazing. Anything else (like if it's the original) and your chances are effectively zero.