Inspiron 5579, random shutdown, support unable to resolve

I own a Dell Inspiron 5579 2-in-1 notebook computer. I have carried a warranty on it from the beginning. In late September, I experienced random shutdowns on battery that required the use of an AC adapter to restart, even with the battery at near full charge. It is random but persistent, sometimes spaced hours apart. While I can use the computer if connected to AC power, I cannot depend on it in mobile setups, because if the shutdown occurs I would have no way of restarting. After extensive interactions with support, I sent in the computer to be repaired. It came back with the same issue. Again I had extensive interactions with support, trying many, many procedures to rectify the problem. None worked. I was asked to send it in a second time. (as a side note, I still had the box and packing from the return of the first service, but rather than just email me a shipping label, the support tech insisted they had to send an entire empty box to me. What a waste of your money and my time!). I sent it in for repair a second time. It was returned with the same problem. In one interaction, I was told that the motherboard had been replaced. I was asked to leave the computer on the diagnostic page to see if it happened. It did not. However, the shutdown is random and sporadic, so this is not conclusive. It just might not have occurred at that point. Anyway I was asked to perform a clean install of Windows, which I did. The problem persists. I’ve been through two remote service sessions as well. No errors were found. Note: there was a recommended critical update to a driver that would not install. After a long session on chat trying to resolve this, the tech gave up and just said that sometimes the computer will not allow a driver update to install, even if it is identified as needed by Support Assist. Wasted another hour and a half. After another extensive interaction with technical support about the random shutdown, I was told that it had been narrowed down to the hard drive and I could send it in and they could replace it and the motherboard. I said that I was told the motherboard had been replaced. AND the problem persists whether the HDD is installed or an SSD (tried 2 different ones) is installed. Does replacing the HDD make sense at any level, given this information? Not in my mind. Nonetheless, I agreed that they could send me a new HDD to try, even though it is illogical. I really do not know if the techs are not thinking things through, or just not looking at the facts on hand. Either way, the support so far has not resolved the problem and at this point it really seems that they are grasping at straws. I would invite you to look at the recorded twitter, phone and chat sessions to see the flow of this issue. It has required me to spend many hours between troubleshooting with the techs, reloading systems and software, prepping hardware, remote testing … only to find out that the problem has not been fixed. On top of all of this, my warranty was to cover on-site service, which has not been honored. Each time the computer is sent in I lose a week an a half of productivity, to say nothing of the time that the computer becomes unproductive because I have to clean it for repair again. Dell is better than this. Or at least I expect it to be. I would ask that you help determine a way to find a resolution to this, so I can stop wasting my time (and yours) going around in a guessing game circle, where communication of basic information seems to get ignored or lost.

Thanks in advance for your help.