controller unlocker timer failed. No start no nothing

2004 tahoe P59 ecu. Went to change the tune just a very minor idle adjustment and when erasing I got the message "Controller Unlocker Timer Failed". Disconnected everything and turned truck on/off tried again same thing. Disconnected battery tried again same thing. Disconnected battery for longer (About 30minutes) and disconnected and reconnected blue and green ecu connectors to get the same failure again.

Battery is less than 6 month old AGM that shows 12.4volts.
Hardware and software are both up to date.

I've probably flashed 30 writes onto the truck with no issue other than it always fails boot down loader in high speed mode so I just un-check that box.

Truck won't start can't even move it out of the driveway to get my backup daily to work tomorrow.

Is my ECU bricked? If so how?
Any chance I can fix this tonight?

Is there any aftermarket radio's or alarms hooked up?

That could cause it not to read/write.

After market radio yes no aftermarket alarm, but it was installed long before I started writing new calibrations. I also turn the radio off along with head lights, interior lights and ac controls everytime I go to write.

Is there something with the after market radio I can check?

There is a kinda new syptom when I disconnect the battery and try again it zips to the erasing stage and then sits there for a minute or 2 only to fail erasing. Then if I try again it goes back to Controller unlocker fail.

Just unpluged radio and amp even switched USB ports on my laptop no change.

Further evidence its likely bricked is that my Ultra Gauge won't connect to it anymore. Guess Ill go pull the ecu off my other truck and try.

Swapped ECUs and the first try had the same error. Second try reminded me I was flashing using the wrong OS since my other trucks on a 4 bar map. Now I'm writing entire on low speed and its 20% through. Looks like it might actually work. Fingers crossed

Write entire failed the first attempt it stalled at 30.8% and had the same error as before. Second attempt took about 20 agonizing minutes but it works and I just dumped the clutch and did donuts in my back yard yehaw!

To answer my own manic questions and possibly help someone else in the future since the only info I found during my searches was from 2018 or older and was not resolved.

ECU bricked? Very possible

How? No idea (possibly a bad ground or connection somewhere. Going to inspect obd2 port better in daylight)

Can I fix it tonight? Only if you have a spare ECU around and no HOA to fine you for tearing up your grass.

Also a tip is not to load tunes blocking your backup daily in garage.

if it failed during write entire its bricked, you should not be doing write entire when you have an issue flashing write cal only. This will ALWAYS end poorly.

Bill Thanks for the reply.

The original ECU failed multiple times during just a write calibration. The second ECU I used did fail during a write entire but I attempted again and it worked without issue and I've been driving on this ECU since. I have a bench harness on the way to hopefully revive the first ECU. Once I have a spare again I will start digging into the root cause of the problem and update this thread. My guess is radio chime adapter, bad/loose OBD2 pin, or a ground problem which could explain my occasional P2135 code.

*edit* I guess at the time I didn't stop to think how reckless it was to throw another ECU in when it was likely to brick it.

Finally got the bench harness. On the first attempt I was able to save the P59 that was repeatedly failing while in the vehicle. I checked the pins on the OBD2 port in the tahoe and they appear to be functional and no pins feel loose. I also checked all the major grounds including the ones on the back of the engine and they also appear good. I have not done any investigating on the radio chime adapter but that will be next. Just glad I don't have to find a new ECU.

This bench harness is really nice to have wish I had bought one long ago I feel anyone who tunes should have one.