To resurrect Nicad battery, Before you going to check your battery first you need to do is check your charger,If the charger is working, you either have an internal open circuit or other charging circuit problem in the battery or one sonny battery that isn't going to be 'resurrected'. If the charger works, only checking of wires or cutting into the battery pack can tell you if it can be 'fixed'.
Actually it's rare to see a *true* ZERO (even a little voltage disqualifies it from the following explanation, yah! before you do that due to a cell failure in a battery pack then if the charger working do the 1st step.
Secondly, check the charger to assure it is actually providing voltage. The only proper way to do that would be to place the meter across while charging to assure it was holding a reasonable float voltage (should be a fair bit above rated battery voltage). Ideally, you'd want to measure current with an ammeter in series, but that's not as easy to put together in most cases. If nothing can be readily measured with the battery in place, at least take a meter to the charger to see if you can pick up float voltage. There's no assurance with that measurement alone (could be being pulled down to zip even under a slight load) but it's better than nothing.3.)You say 'battery' and not 'cell'. If it's a battery pack of some sort, it may well have internal charging circuitry (some contain 'intelligent' electronics) -- or at a minimum, should have a temperature cut-off device (thermal breaker) to avoid any dangerous overcurrent conditions during charging or use. The charging circuit or internal breaker *may* have failed. Further, if it is a true 'battery', the cells are internally bonded together. It's not common that these bond straps break (they're usually spot welded to the cells), but hey -- anything is possible.
4.) Don't assume it's the battery itself that has failed (again, assuming it's not just a single cell). You may have lost an internal connection or may be dealing with a loose external connection. If it's one of those packs that come in a portable phone or R/C car (just as examples), a tiny tug on the wiring between the battery and connector may provide a surprise, and that'd give you zero in a hurry. If the charger is good, and you can't sort out the problem, and it's some sort of battery pack that's a bugger to replace, you can take it to a place like Batteries Plus to have it rebuilt with new cells. While you're at it, you might also consider switching them to NiMH for better capacity and lack of the 'memory effect' that is a problem for NiCd cells.