Codes P1626, B2961 and U1064

So initially someone had driven the vehicle parked at friends and then went to leave and it wouldn't start again. Just cranks but not actually firing over. I came and got the vehicle. My friend at the time had more knowledge about vehicles so he looked at it and said the first thing was he saw the fuse for the BCM was missing. He said he had one, so he put one in that spot. Also, the security light would flash constantly. I tried the key relearn thing, friend put a resistor in under the steering wheel, and eventually the security light did go back to normal. And still is like it should. It will show on dash like the rest of the lights then go off in a second or two. But the vehicle still just isn't actually starting. We had to replace the starter just 2 months ago. I have had to put a charger on battery a few times because of how cold it's been outside here and the fact that it's not ever running to charge it I assume. We did a fuel pressure test a few months back and it was okay. I hear the fuel pump kicking on when I turn the key also. I really need this blazer fixed (1. It's my father's, who went ER in March, was severely sick, got transferred nursing home for his level around the clock care and had put him on ventilator and feeding tube) sadly he hasn't been able to come home since that day he left to go hospital in March last year. He asked that I take care of his vehicle and in return he let me drive it as I usually did to take him doctors, store, or if I needed to go anywhere. I have an older sister who isn't as responsible as I am, she had a key also to the blazer, and she drove it a few times with her boyfriend. (Neither have license) is why father told me to try and not let her especially drive it. Well, I noticed her boyfriend would mess around under hood and remove a fuse or plug here and there to make it seem like blazer isn't running, just so that I wouldn't come and drive it anywhere. They'd have it all to themselves. Well, she said she drove it to friends. Then they went to leave, and it just wouldn't start. And hasn't since. It's almost been a year! I don't have any way to get anywhere right now. I have severe social anxiety that makes it hard for me to even leave my house. I want so badly to figure this out and have it driving again so I can see my father who's only a 20-minute drive from me and tell him his vehicle is back on the road again. He has lost a lot his good spirits last few months and I just know he will be so happy hearing that news and seeing me visiting him daily! Always been close to my father. And I was taking care of him best I could until he went to hospital in March. Anyone any advice, suggestions, please get at me thank you sorry this is so long kind of wanted help fill y'all in. -Katie-