mspiff In the live USB you have some choices:
1)Disks will CHECK boot and REPAIR BOOT if necessary. I never resize in it. I don't think you can.
2) GPARTED [see all my pics at beginning of thread] WILL check the boot partition if you select the boot partition. Gparted will FIX errors on the /boot partition if there are errors. ****Note: none of this check/fix stuff resizes your partition. you need to do that in gparted (again see my pics).
so what exactly of these two tools--or other tool?---detects you as corrupted? Because these two tools can likely repair that. Is that what is holding you up?
Also for the rest you wrote: you can't invent a new boot for an existing operating system by deleting then creating and re-setting flags. It's a nice idea, but files from the install--including latest kernel---have to be in that partition I think.
****I am 100% sure you can resize this to 512 but I am 0% sure you can recover you operating system because you have to mount it (CHROOT) to repair and update boot drive with the latest kernel. I know of no way around this but Linux Expert I am far from
I also wonder if that CHECK/REPAIR function both tools (Disks & Gparted) have would work on the /root (main filesystem) partition as well? What do you have to lose? What I'm getting at is this: maybe your TTY terminal will be restored on a reboot after check/repair.
If you have terminal access you have everything. Maybe shift direction here? I am like you. I would move heaven and earth to recover what I do have rather that start over. ..............the really crappy part of having a mindset like this is you will succeed.....in a month or next year or tomorrow but probably 2 months🙂....the sh*t you can throw against the wall to see if it sticks seems infinite🙁