Well it’s not going to boot if the UUID is not correct. I think now at least if it’s set to AHCI you can rule out that causing it to get the wrong UUID. You would most likely have to chroot into the system from the live ISO again and correct the UUID. @manuel is better to go through that with you. I’m not very good at spotting what needs to be changed.
Edit: I don’t think your stuck. You just have to be prepared to work through it.
perhaps this helps to figure out the problem
[root@archiso /]# sudo grub-mkconfig -o /boot/grub/grub.cfg
Generating grub configuration file ...
Found theme: /boot/grub/themes/EndeavourOS/theme.txt
Found linux image: /boot/vmlinuz-linux
Found initrd image: /boot/intel-ucode.img /boot/initramfs-linux.img
Found fallback initrd image(s) in /boot: initramfs-linux-fallback.img
grub-probe: error: cannot find a GRUB drive for /dev/sda1. Check your device.map.
done
[root@archiso /]#
Did you have the usb drive in when running the grub command because it will give you that error. Your drive is an m.2 drive named /dev/nvme0n1p2 which is the root partition. Did you arch-chroot into the system from the live ISO and try reinstalling grub and updating grub since you found the RST setting and changed it to AHCI? That’s maybe what i would try.
hi rick, admire your Persistence!
yes i booted off the live usb and then archchooted in, as you showed me previously, followed the same prototcol. (so i have the usd drive in )
[root@archiso /]# sudo grub-mkconfig -o /boot/grub/grub.cfg```
do i need do something different.?
note in most recent setup p1 is the home and p3 is the eif bootDid you follow the Wiki to repair grub & reinstall it and update it?
fgos, i updated grub as above, then rebooted. still no joy. same cannot find uuid issue
nals
You’ll have to edit it manually.
I’m not sure if that is enough. Have you rechecked that it is AHCI and not RST?
And every time when you change something with the disk, please provide us more information about the current disk status, something like
lsblk -fm sudo fdisk -l # on the arch-chrooted system: cat /etc/fstab cat /boot/grub/grub.cfg
Otherwise we are helping you based on wrong information, and that unfortunately may just waste everybody’s time.
thank you manuel,
confirm have checked is set to AHCI
lsbk -fm output
| curl -F 'f:1=<-' ix.io
sudo fdisk -l output
| curl -F 'f:1=<-' ix.io
however cannot get to the chrooted system
[liveuser@eos-2021.02.03 ~]$ sudo su
[root@archiso liveuser]# mount /dev/nvme0n1p1 /mnt
[root@archiso liveuser]# mount /dev/nvme0n1p3 /mnt
[root@archiso liveuser]# arch-chroot /mnt
mount: /mnt/proc: mount point does not exist.
==> ERROR: failed to setup chroot /mnt
[root@archiso liveuser]# arch-chroot /mnt
mount: /mnt/proc: mount point does not exist.
==> ERROR: failed to setup chroot /mnt
[root@archiso liveuser]#
followed the same instructions that rick provided and worked previously
Unfortunately all the commands you did above are incorrect.
Please be careful when running the commands. Otherwise you’ll get nothing useful with them, and even can make situation worse.
Hello @nals
Thanks for trying to provide some more information as requested. You didn’t post the outputs properly. I think it is a misunderstanding how to do it. Also i think i missed one step when i posted how to arch-chroot and i thought maybe you would follow the wiki. Sometimes we make mistakes too. 
Boot on the live ISO
sudo su
mount /dev/nvme0n1p3 /mnt
mount /dev/nvme0n1p1 /mnt/boot/efi
arch-chroot /mnt
You can use the following with the above commands and it will automatically post the info to pastebin and provide you a link. You just need to copy the link address and post it under the command you use.
lsblk -fm | eos-sendlog
sudo fdisk -l | eos-sendlog
Edit: @manuel i hope i got this right as i see you beat me to it.
You have a typo in the last command… 
I don’t see it? 
Pipe missing.
See i do make mistakes…many! 
That’s understandable, and the “funny” part is that after making a mistake the writer is blind to it. Happened to me too, many times.
Are my instructions on chroot correct? I think i have only done it twice in my life! 
Edit: I hope you can help from here if @nals can provide the proper info as i am not well versed with fixing grub.
Looks OK, but of course depends on what actually is on the disk.
I’m not sure about the latest partitioning because of those failed commands (fdisk and lsblk) above.
Grub is easy! But the problem here most likely is not grub. Let’s see what comes out…
Well …i just thought that it’s hardware as i have installed EndeavourOS at least 500 times and i believe that 99% of the time there are no issues. The remaining times it’s either user error and or hardware issue. Here i think is to do with software raid. I could be wrong but well see.