What worked in my case it is a new, charged (maybe over charged) MTH 50-1008 green rechargeable battery.
The facts:
I bought on ebay a Centipede Set 20-2200 equipped with QSI. I installed a new 50-1008, that I charged for about 2 hours; it showed about 11V on analog voltmeter. Did not move, 2 bangs, compressor sound and nothing else.
I tried everything that you shared on the forum (for which I cannot thank you enough) including re-set 18 with a MTH Z-4000 with no positive result.
I took the battery out and I charged it for about 6-7 hours; the needle of my analog voltmeter was strongly banging at the end of 10V scale.
I installed the battery in the lead unit, gave power under 10V and then 0V and when I powered again started to move. No re-set 18.
Thanks again for all your experience shared on the forum.