Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
I do not know what co. you were in touch with before being cut off, but it seems not to have been JustAnswer.com.
After you put the new batteries in, did it show any signs of life? if not, if it showed no lights nor beeped at any time, and if you have never been able to open it since then (i.e. if this attempt to open it that failed, was the first such attempt), you may have inserted the batteries wrong, or had one dead battery among them, or something similar.
Some safes have emergency keys, that can be used to open the safe in cases where the batteries are dead or the electronic keypad is somehow inoperative. What maker and model # ***** safe do you have? if it's a model with such a key, I suggest you use it, and check the battery compartment with some care, for terminals no longer shiny owing to corrosion or other reasons for the batteries to not have allowed the safe to work normally.