2014 Ford Edge - Wont Start After Sitting

My son’s Ford Edge, Sport, AWD won’t start. It’s been sitting since Dec. 2018 when he went into the hospital for a partial leg amputation. The battery was weak and went dead. I replaced it about April this year. I even had a nice local mechanic come to the house, for $20 if he could get it started by hooking up his computer to try and clear any codes, including a security code. He said he cleared all but the security code. I gave him the $20 any way just for coming to the house and told him that I would stop and give him the solution if I could find out what it was.
I had one mechanic give me a series of entries with the key fob, but, alas, it didn’t work.
You are my last hope before we have it towed to a Ford dealer so that they can hook it up to their computer to restore it. With towing, probably $150 to $200.
Sorry that this is so long a description. The more information you have the better.
Thanks for any help.

Have it towed to the Ford dealer.