What causes lead acid batteries to go short?

[brainwash]

I bought a broken car starter helper from ebay and it has a 22Ah VRLA battery inside that is shorted. I've never met any batteries until now that have all elements shorted. I assume since the battery was dry all the shocks (transportation) caused the lead plates to break and fall on the bottom of the element shorting it. However, it's not clear to me and I cannot find any explanation anywhere.
I've revived dead batteries and recycled ones with one or at most two elements shorted, but never met any one with all of them shorted.

I've let my trusty Accucel-6 charger charge it in NiMH/NiCd mode at 3-5A for about 8h and it still reads zero while drawing maximum amps, so the battery is beyond saving.

[brainwash]

Sorry, you can ignore the post, the battery was 'fine', the actual circuit inside the starter is shorted, which is good news. It was stupid of me to not try to disconnect the battery and assume the circuit was ok just by testing with some leads removed.

[brainwash]

Battery started holding charge after ~40h on a supply at 14.4V/1A. Yesterday it was only holding 5V, today is holding over 10V.
For anyone else trying this (I did it many times): make sure you do it outside, vent caps off or loose, limit the current to at most 1/10 of capacity, make sure there is enough liquid. They will never hold the initial charge nor provide the crank amps, but they will perform at 30-70%.

Regarding the topic of reviving batteries, is there any study on CC/CV supply vs pulsers? I have never used a pulser but I don't trust voodoo magic and would guess in a controlled test they would perform exactly the same. Has anyone done a comparison?

[KJDS]

There has been far more work done on NiCad and Li-iion, none of which I've looked at in the last twenty years.

There are some advantages to charging those with a pulse, especially on larger batteries. however the only real issue to lead acid is boiling the electrolyte off.