Full flash fail, now getting checksum error - can't reflash

[Wackpow]

Hello everyone!
I'm having problems getting my ECM flashed back to any type of working state. I was performing an OS upgrade to DSP5 and had the full flash process fail with ~30 seconds remaining. Since then I have not been able to get the truck working again. I have tried re-flashing the same DSP5 OS, the original OS/calibration, and even a stock OS/calibration from Holden Crazy (tunefiledepot.com). Each time I perform a test flash it starts with an error: "EFILive has detected that this ECM may not have a valid calibration" and will go all the way through the test, then ends with "Status:Calibration missing" and a Checksum failure. I can perform a Cal Flash without errors and get a "successful" message afterwards, but when reading a calibration after still get a checksum error relating to the operating system.

A summary of my troubleshooting and what I've tried so far:
- Full flash and Cal Flash with both V7 and V8 software (and tried updating to the most recent version/build)
- Removed all the fuses for radio/info(OnStar)/lights/trailer brakes/ABS/HVAC/etc.
- Charged both batteries in the truck to ensure consistent power throughout the process
- Tried unselecting "use high speed"
- Selected "Try Alt Keys"

Forgive me if I'm missing something simple, but I've tried everything I can think of and searched through countless other forum topics, but can't seem to come up with a solution!
Shouldn't it be as simple as taking the original calibration I read from the truck before trying any tuning and full flashing it back?

Truck is a stock '05 LLY
Stock OS 15231600 / Calibration 15231599 with a checksum of $4319
Current OS (failed DSP5 flash) 5160005 / Calibration 15231599 with checksum error of $CF0B

Thanks in advance to anyone with ideas!
Tom

[IdahoRob]

Is the truck running? Does it run with the successful cal flash of the stock tune in it? Did you script/populate the DSP5 converted tune with dsp5 script to complete all the dsp5 tables?

[Wackpow]

No, the truck won't start at all, not from any of the cal flashes or full flashes.
Yes, I did run the script on the DSP5 tune to try to correct the out of range tables, but this didn't seem to correct things.
Would you suggest running the script again and copying over my stock tune into the DSP5 tables as a starting point, or would it be easier to try to get things back to stock without DSP5?

[IdahoRob]

Umm, sounds like battery voltage dropped during full flash. Can you communicate with the ecm at all, scan tool, check/clear codes? Have you looked at the "stock" tune and compared it to a true stock tune of the same OS and seen if it is truly stock? ECM fuses ok?

[Wackpow]

I did pull both batteries and give them a full charge before my 3rd or 4th round of attempts along with pulling all the light fuses to prevent battery drain, so I would think voltage shouldn't be an issue?
There weren't any blown fuses, including the ECM fuse.
I get errors: "ECM is an unknown state"
I will re-scan tonight and try clearing codes and see what/when exactly the communication to the ECM is.
As for comparing my original "stock" tune to one from tunefiledepot.com, no I haven't done this yet.
Thank you for the suggestions, much appreciated! I'll check these couple things and let you know.

[Wackpow]

So I've finally tried scanning (I've been out of town and haven't had a chance to follow up with this problem sooner).
When using the scan tool, everything seems to connect fine except for a message of "Operating system number could not be determined"
When connecting with the tune tool and "Check status" prior to a flash I get a message stating it doesn't have a valid calibration. I'll continue to read it anyways and everything will go fine right until the end when I get an error of "Calibration contains one or more incorrect segment checksums" even though the final message on the console window is that the flash was retrieved correctly.
I also tried another full flash test flash and everything goes fine right until the end when I receive an error of "Checksum of flash failed after write completed. Please reflash the controller. ECM is an unknown state"

Also, to follow up on a previous suggestion of looking for differences between my original calibration and the one I downloaded from TuneFileDepot, it is pretty much the same. A couple tables had several small differences, but I don't really know what in particular I should be looking for...

Is my ECM toast?
Should I try an actual full flash again with the stock calibration or of the DSP5 calibration?
I'm really stuck for what my next step should be!

[Wackpow]

Update: I was finally able to get the ECM back programmed with the original stock tune/OS.
I tried multiple full flashes with the DSP5 OS/tune in V7 and V8 along with cal flashes in both. Each time getting errors and not able to have a successful flash. After each failed attempt I would have to pull the PCM fuse in order to detect it for the following flash.
Finally I was able to get a successful full flash of the original tune and only when I unchecked "use high speed."
I wish I could pinpoint exactly what allowed it to work this time, hopefully helping someone else in the future with similar problems, but all I really know is its working now.

Thanks IdahoRob for your suggestions along the way!