After the 1st charge I used a screwdriver but then it stopped charging. I've been trying this for the past 3-4 days. I think the batteries are old/discharged. I don't want to open and change batteries. Can you suggest how to deal with this? Do I have to return the entire package and get a refund, or can you send a new screwdriver in the return package and I will send back the screwdriver you sent last week? Many Thanks