has anyone tried this??

[egginyourface]

Fixing NiCd Drill Battery's For Free - YouTube

 

[Inteificio]

couldn't be arsed to watch it as 8 mins long.

Just a guess are they pushing a high reverse voltage through the cells?

Not sure if it would work, depends why the battery is dead.

It is generally easy to repair, normally just one of the cells is ****ed.
pop open your charged battery.
check the cells one by one, firstly voltage, but if that doesn't point the dead one, use a high current drain device and check for current and voltage drop.

then cut out the dead cells and replace with sub-c size.

simple and can save A LOT of money!

bestofferbuy can get you the cells for cheap (but slow)