Let's see where we are and what I (mis)understood:
- You did run 4 bitcoin services, miners make extensive use of the computing power of graphic cards, so either your miner or some intruder is using that card
- Your servers are blocked from sending data
- Your bootmanager is corrupt, from the November 2020 update?
- You did run Bitlocker on that machine
- It behaves like Spectre virus has taken over
What else can be done than trying a new and clean install, avoiding all previous obstacles, hence using a new MS account, and clean installation media.
I did not read that you got new media, only a new license.
One option would be:
- create from a different PC a new MS account;
- if you don't have a clean and bootable USB stick with Windows installation media, create one on a different and clean PC (ask your son?),
see here for instructions;
- Back to your crippled PC, you have to push, during power up, a specific key several times, or keep it pushed down, look in the manual page, it is often F2, to get into BIOS, find Bootoptions, and select your USB stick.
Or is this a 'bridge to far'?