Rechargeable Batteries..18650's..

Right, I've got about £250's worth of lights, £10's worth of which I can actually use.

The majority of the problems stem from the battery packs.
The first one is a Magicshine pack that contains a sealed pack of 6 18650 batteries. It's virtually brand new but may of either been over discharged or stored without enough charge. Either way it won't charge. I've tried a new charger and nowt.
Same thing goes for a Cree battery pack, x4 18650's. Used once and unwittingly over discharged, charger supplied is faulty so light showed green for about 10mins then straight to red then out and now will not even attempt to charge.

I've read that quickly shocking them back to life using a 9V battery can cheer them up to charging level. I have no idea how that works.
I kinda of get it for a single battery without knowing the exact method but how do you do that for a x4 or 6 pack?
Do you have to touch each individual battery + and - ?
You can't do anything through the connector plug?

You'll have to bear with a bit as I've got absolutely no clue about electronics..

Also is it easy to fit new connector plugs to the end of the cables? Can you reuse the old connector?

I can supply photos if that helps.

Does anybody know anyone or where I could take all this junk to get sorted? North or East London?

Ta.