While I can understand the problems you are describing, I'm not really sure what help you're asking for. Can you be specific about what help you need here?
In terms of needing to install WIndows from a USB then whether that works or not is dependent upon your computer's firmware. In my experience, creating a bootable USB drive is problematic for even new computers. I believe the minimum size of the USB for NTFS is 8 GB. Ensure your USB is larger than that. It may copy the files if it is under that but it won't work. Using the FAT system also may work but that requires you break up one of the setup files manually as it is too large. There are lots of sites online that discuss how to create bootable drives but I found using the MS Media Tool available here to be the best option.
Many modern motherboards may or may not even enable the USB ports before the OS needs to start which makes booting from a USB difficult at best. In many cases you may need to go into the BIOS and disable features like fastboot and ensure that the motherboard powers on the USB as early as possible, depends on the motherboard. Otherwise the motherboard may try to quickly boot into Windows without worrying about anything else.
As for Windows booting up correctly one day and not the next, Windows creates a bootable partition when you install it. This bootable partition is where the computer starts and is independent of the OS(es) you may ultimately run on that machine. Assuming that partition is good then it is possible to boot into Windows (or another OS) irrelevant of the state of the Windows setup.
The problems you are describing sound to me like hardware issues in one of the core components. The motherboard, memory, PSU, CPU, etc. Unfortunately diagnosing failures here could be hard. If Windows BSODs then it'll log something in the Event Log first. If you are able to boot into Windows then I'd go there to see what it says. If you cannot even get there before your machine shuts off then I'd lean toward a PSU, motherboard, chip, memory or temperature issue. Most modern motherboards allow you to boot into the BIOS where you can run basic tests to help determine hardware issues. Otherwise your best bet is to use a bootable USB for third party tools like memtest86 to test other components.