Replacing an ESC - help needed.

I bought a 680 pro build from Craigslist and have been upgrading and adding gimbals etc. It has flown a few times and done very well being stable in loiter etc.

Recently, after solving a loose prop issue (solved now) I discovered a bad drive. I say drive because I all I knew at the time was that one motor was nor behaving.

After bench  testing and further investigation I isolated the problem to the ESC. Not the port on APM, not the power, not the motor. I took it apart and one of the leads was not well soldered. Stupidly I thought I have found the problem, re-soldered and lauched the hex. It flew, but I had no control over the throttle. It either climbed or dropped like a stone. Other degrees of freedom worked but it was't pretty. 

After a while and a couple of take offs it landed hard and the ESC in question burst into flames - my first literal "crash and burn". 

Back on the bench I had spare / replacement ESC's (that came with everything I had acquired) and attached one. When tested it operated but was not keeping up with the other 5 and starting a higher throttle.

I calibrated the throttle (all together) but made no progress. Contacting the guy who built it I found out he had used SimonK on the ESCs. That was a good to know. I acquired a UABasp programmer and flashed the new ESC succesfully (according to the messaged in the KKMulticopter flash tool).

I had achieved something because now the motor doesn't spin at all.

I took a second spare ESC, tested it, flashed it and tested it again with exactly the same result. 

These are Hobbyking 30A ESC (green). 

Faced with this, what would you do? I have no reason to suspect that re-flashing the other ESCs will do anything other than brick them too.  

I thought flashing SimonK on the new ESC then repeating the throttle calibration would fix my problem. Have I missed a step.

All suggestions, questions welcome.

Oh APM2.8, Flash tool 0.77, tried a lot of different versions of SimonK (not sure what all the differences are. I used "ATmega 8-bit brushless ESC - with bootloader" for the programmer. 

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