Earlier this month, the latch on my back hatch door broke and the hatch wouldn't lock closed. What I hadn't realized was a rear dome was popping on and off when people bumped the truck and at some point it apparently remained on. One day I came out to a dead car; I jumped it and drove it to a different spot on my property and pushed the door down to where the light stayed off and parked it. Two days later (July 3) I had arranged to get the latch fixed and it had to be jumped again. Once I reached my mechanic about 15 minutes from my home, I warned him that I may have killed the battery and that it may not start without being jumped. He fixed the latch and the car started right up. The next few days the car was used here and there but it sat all weekend without driving. On Tuesday the 10th I had a Dr. Appointment 20 minutes away; car started fine, I went to it and it started again fine when I returned home. I parked the car that day until yesterday (15th) I tried to start it and it was dead. Today I attempted to jump it and it would not jump for anything. Just the clicking noise-tried for 20 minutes. What is up here? Just the battery or could it be something else? The only other possibly relevant info is that it has been around 90 degrees during all of this time I described.
If the vehicle battery is very flat (discharged) then that can cause the jumping battery to struggle to start the car - most jumping batteries are smaller in capacity than the original vehicle battery ...
Unless, you have an auto-electrician who - like I did - takes a commercial vehicle battery that is about 6 times larger than a car battery and mounts that on a wheeled trolley with some very heavy duty starting cables with good clamps : they always started :)
You should first thoroughly charge the vehicle battery then see how it behaves - once that battery is fully charged then you can check to see if the alternator is charging etc.