A battery dead for five years can be compared to a human
Heart stopped beating a minute ago
Administer vigorous CPR
Heart stopped beating 5 years ago.
Gimme a break. Even spending 3 months discharged ruins a battery. Yes they will light up a test light after twelve dollars worth of electricity is dummped into it. Even massive resusitative efforts will bring a relatively recent totally discharged battery to store some power if you are looking for dependability forget it. Autopsy it and you will find plate material sulfated to the grids or even missing. Trying to nursemaid a damaged battery is like trying out freeway speeds with a tire with a boot in it.