Inspiron 15 7537 Login Screen Freeze after Windows 10 Installation

After running Windows 8.1. on my Inspiron 7537 for more than 3.5 years without a single issue, I decided to upgrade to Windows 10.  Installed Windows 10 with bootable USB flash drive after formatting and creating two partitions on my SSD. Installation went smoothly and successfully. The system would operate smoothly for about 2 hours. I customized some stuff, installed extensions for Edge surfed in the internet using WIFI. All of the sudden it would crash, I rebooted without any issues. After a couple of minutes it would crash again and from this point on reboot would only work until the login screen. As soon as I entered my  login password it would freeze. I tried to reboot tons of times.

-Booting in Secure Mode works well, no issues

-Dell pre-boot system assessment worked well, no problems diagnosed

-Windows Startup Repair didn't work

(-Windows service hotline/chat was a waste of time)

-tried to format and reinstall Windows three times, problem remains. After some time it would crash, and then upon entering my login password the login screen freezes.

I am on a work assignment in Ethiopia. Internet speed here is really slow. Within these 2 hours (after first installation. It was about 60 minutes after the second installation.) that the system worked perfectly fine I tried to download the missing Dell drivers (Touchpad, Nvidia graphic drivers, etc) but could not finish it until it crashed because the internet here is too slow. Also in the background it keeps automatically downloading windows updates. I kept the boot setting in legacy mode (switched off UEFI and secure boot in order to boot from the USB drive).

I have no idea what it could be and why the system would run smoothly for some time, then crashes and then freeze when logging in. Do you have any ideas, suggestions, solutions?

Thanks heaps.