After pressing every key combo suggested by every article known to mankind 
the original drive also produces just the beautiful white screen.
I find it quite interesting that it decided to do that after you put in that DVD. By the way, is the SuperDrive still spinning even without a disk inside?
I have no idea which key combo was the final nail in the coffin, there were so many. But when I first tried the DVD, it did nothing but continually spin when the MacBook tried to read it.
It is nice and calm now with no DVD in the drive.
Does the Command+R do anything once you hold it during start up? Normally it should take you to rescue mode. Especially with its original drive back in.
It will not go into recovery mode. I told you I killed it! 
I think the last thing I tried was a 4-key combo something like: (option+R+command+P) and it gave up the 
I tried the link for Budgie you posted, but it didn’t work. Is is Manjaro Budgie or Ubuntu Budgie? I found the download page for Ubuntu Budgie but not Manjaro B.
I’m going to attempt to use the External DVD with my '15 Mac since I just did an update on Big Sur. Maybe it corrected whatever was keeping it from being recognized…
The best news out of all of this is my external DVD now works on my '15 MacBook Pro! This should make things a little easier. 
My link was the Manjaro version of the Budgie Desktop Environment. Its boot loader is a bit more agreeable, that’s why I thought of it. 
If the 4-key was the combo that made your MacBook freeze, perhaps it will allow it to reset again via the same combination (and be left on for a minute). Let’s hope this will give it the “cup of coffee” it needs to wake up!