Hello, I'll help as much as I'm able, with the understanding that I can't help you circumvent the unknown admin password issue, but I may be able to help identify why it's BSODing.
The first thing I'd want to know is what happened to make it stop booting? You just say that "it won't boot" but it would be useful to know what happened prior to this problem occurring. If something was working and now it's not, then something has changed. What changed? That may be a big clue.
Please disconnect all external devices except for the mouse, keyboard, and one monitor. Then see whether it will boot?
You mentioned that you have a dump file from the PC? Please upload it to a cloud service with a link to it here. Please ensure that we don't need to login to download the dump (ie. make it public).
The 0C000021A exception code you get with the BSOD is a SYSTEM_PROCESS_TERMINATED, which suggests of course that one of the critical Windows processes terminated during the boot process. The most likely cause of that happening is going to be a hardware problem and bad RAM is one of the common hardware problems.
On another PC download
Memtest86 (free), use the imageUSB.exe tool extracted from the download to make a bootable USB drive containing Memtest86. Then boot that USB drive, Memtest86 will start running as soon as it boots. If no errors have been found after the four iterations of the 13 tests that the free version does, then restart Memtest86 and do another four iterations. Even a single bit error is a failure.
If you have a Windows installation system on a USB drive, does it boot that OK? Is it stable running that OS? Can you navigate via command prompt to all drives and all partitions? You might do better using a USB drive made with the
Windows Media Creation Tool rather than an ISO burned via Rufus.