Luis - my suggestion to you is leave the battery testing & repairs to the battery & charger dealers who are trained to do this type of work. You will only get yourself in to a lot of trouble trying to save a few pesos & end up destroying a possible good or at least salvegable battery and waste a lot of time & more many more neuvo pesos doing it. Leave it to to the experts - it really doesn't cost that much.
For example, if you do not correctly acid balance the electrolyte in the cell you will destroy the cell, or cells, if the connector are not installed properly you will destroy the cells. Also to check the batteries health it takes about three days to do it properly. Don't think this forum would be a good place to get training on how to do it - too many liability issues w/over the internet training especially with an item that has acid & can blow up.