help 2003 silverado flash fail now unable to locate vcm

[dangerous95lt1]

Working on a 03 silverado read the pcm it kicked me in low speed mode and completed the read
Went to write the calibration and it failed
Showed recovery tried the recovery flash it completed but could not verify
Now it just says unable to locate vcm no matter what I do I have tested voltage it is 12.3 with key on
I tried pulling audio fuse
Nothing I have charged battery still nothing
I have disconnected the battery and retried to connect unable to located vcm
Truck will not start or crank over its just dead in the water
Any help please?

[Road]

Do you have beta 2.25 if so you might try doing a write entire

[2xLS1]

I have found that once you disconnect the battery there is no chance of recovery on P1 and P59 PCMs. I'd say it's new/used PCM time. Those are readily available around here for $25-$50 at salvage yards. Does the truck have an aftermarket stereo?

[dangerous95lt1]

Didn't try to flash it on the beta.
Yes it does have aftermarket stereo

[2xLS1]

The aftermarket chime adapters between the aftermarket stereo and harness can interfere with reading and writing on 03-07 classic trucks and seem to be hit or miss. The factory radio has something to do with PCM communication through the ALDL. Anytime you encounter a read issue on those vehicles with an aftermarket radio you should pull the radio and radio amp fuses especially before attempting a write. Aftermarket alarms and remote starts that tap into the purple ALDL wire can effect PCM communication too.