I once had someone ask to help start a car that had been parked up with no tax or mot for 8 months, so it could be moved. When it expectantly didn't turn over with the knackered battery that had ballooned. All I got was abuse that because the battery/car last ran 8 months ago that the battery must be ok. After another hour or so mucking around with jump leads and trying to jump start it with the jump leads getting hot and the battery near to exploding it was at least trying to turn over, just. But adamant that the battery was still ok, despite it being clearly knackered, the owner had already started looking on eBay for a new starter motor.
After finally convincing them that if the starter motor was knackered, how would it be turning over the engine and that it was the battery. It was then suggested that I removed the working few weeks old battery from my own car I'd turned up in, fit it in place of the knackered one then drive it (with no tax, mot or insurance) to its new home 5 miles away for £20 for my new battery. Then for me to call a taxi to take me to Halfords to buy myself a new battery, to then take back and refit to my own car so I could drive off home.
You can guess my response along the lines of where to go and shove that idea.