The laptop in question is ZenBook Flip UX360CA that's roughly 8-9 years old, it's been a very good laptop. I have been able to backup everything to an HDD and using the Gdrive sync.
The biggest problem is the BIOS will not detect the boot partition and constantly boots into BIOS. I am able to manually add a boot option in the 'boot' menu and point it to the Windows boot sequence bootmgfw. So the SSD is detected. But this has to be done with the boot override; every reset, this additional boot option is lost.

Sometimes, this option to add a new boot option disappears and I am stuck waiting. Shutting down, removing the battery from the power source and rebooting will show it again.

When I do get it booted into windows, I am often met with the critical process died sequence.

The battery also appears to charge very slowly and drain when not plugged in at times. But the battery report isn't awful

I tried putting a WIndows 10 ISO on a USB drive and trying to repair the start up, etc.
I tried booting into a linux with a USB drive to do a few things but had no luck. I tried manually flashing the bootmgfw.efi into the bios settings, I tried running a windows repair
At this point, I'm a bit lost as to what to try next. Should I try installing a fresh version of Windows and blast away what I have now? Attempt to replace the SSD? Time to ditch this one for a new laptop given the symptoms?
The biggest problem is the BIOS will not detect the boot partition and constantly boots into BIOS. I am able to manually add a boot option in the 'boot' menu and point it to the Windows boot sequence bootmgfw. So the SSD is detected. But this has to be done with the boot override; every reset, this additional boot option is lost.

Sometimes, this option to add a new boot option disappears and I am stuck waiting. Shutting down, removing the battery from the power source and rebooting will show it again.

When I do get it booted into windows, I am often met with the critical process died sequence.

The battery also appears to charge very slowly and drain when not plugged in at times. But the battery report isn't awful

I tried putting a WIndows 10 ISO on a USB drive and trying to repair the start up, etc.
I tried booting into a linux with a USB drive to do a few things but had no luck. I tried manually flashing the bootmgfw.efi into the bios settings, I tried running a windows repair
At this point, I'm a bit lost as to what to try next. Should I try installing a fresh version of Windows and blast away what I have now? Attempt to replace the SSD? Time to ditch this one for a new laptop given the symptoms?