I have a fairly new Dell desktop xps with an Nvidia card running Windows 11. I have a 1TB SSD for windows, and a 500GB SSD for Linux. Originally, I was going to install MInt, but I found reviews on Zorin, and I installed Zorin OS 16 pro in a dual-boot configuration. Worked fine for several weeks, then last night I ran update and upgrade from terminal, and it said that I have to restart. It booted past the Dell/Zorin splash screen and stopped on a black screen with a blinking cursor that would not respond. I powered off and at boot I selected Zorin with options. I picked recovery mode, and it booted and worked fine, BUT I would get an error message that the efi/ partition was unusable. WTF! I went to this forum, and it was down for maintenance. How do I get back to normal functioning?
You may need to run fsck. But first, can you please post the terminal output of:
lsblk -o name,mountpoint,label,size,fstype,uuid,partuuid | egrep -v "^loop"
Then post the contents of /etc/fstab so we can compare them against each other:
cat /etc/fstab
You may try the application Boot Repair:
https://www.howtogeek.com/114884/how-to-repair-grub2-when-ubuntu-wont-boot/
Grub Repair sounds like a good option to fix.
I'd like to add, make sure you have SECURE BOOT and FAST BOOT disabled in the BIOS. If the computer is new enough, make sure TPM is off too.
What does "fsck" do?
I will post the terminal output below; I can't do it for about 1-1/2 hours.
File System Check.
It is best to run it after making full back ups (Just In Case...) and when you have plenty of available time. Usually, everything goes well and fast. But not always.
Secure Boot, Fast Boot and TPM are all off, and AHCI is enabled; the thing worked for three weeks, until I followed the recommended update and upgrade. Is the problem a new kernel, or what?
Quite possible; are yuo able to tap esc at boot and get to the Recovery menu, Advanced Options and select the previous kernel?
[quote="Aravisian, post:2, topic:10702"]
lsblk -o name,mountpoint,label,size,fstype,uuid,partuuid | egrep -v "^loop
lsblk -o name,mountpoint,label,size,fstype,uuid,partuuid | egrep -v "^loop"brad@brad-XPS-8940:~$ lsblk -o name,mountpoint,label,size,fstype,uuid,partuuid | egrep -v "^loop"
NAME MOUNTPOINT LABEL SIZE FSTYPE UUID PARTUUID
sda 931.5G
├─sda1 128M c2474ef3-06ab-4c08-a1fe-730170471c6f
└─sda2 DATA 931.4G ntfs E49830E99830BC3C 69f4abef-7d6d-4179-b2e5-67a0e8c87a9e
sdb 465.8G
└─sdb1 / 465.8G ext4 be63ac29-7656-4ace-95ef-72cf242637c3 2ff9e60f-7865-454f-97f7-c79187b7ad49
sdc 1.8T
├─sdc1 System Reserved 100M ntfs 342897B828977796 3119d5b4-01
├─sdc2 /media/brad/12029A4D029A35A71 1.2T ntfs 12029A4D029A35A7 3119d5b4-02
├─sdc3 1K 3119d5b4-03
├─sdc5 /media/brad/DATA1 DATA 99.4G ntfs 01CF6192E0BE96A0 3119d5b4-05
├─sdc6 EXTRA DISK 412.9G ntfs 01CF6192F99ED810 3119d5b4-06
├─sdc7 /media/brad/b6531485-cf61-4aa8-a84f-a974f73558161 77.2G ext4 b6531485-cf61-4aa8-a84f-a974f7355816 3119d5b4-07
└─sdc8 16G swap 436af5b9-2c2b-439c-8a94-aeb40e92faa6 3119d5b4-08
sdd 2.7T
├─sdd1 System Reserved 100M ntfs 342897B828977796 a4ed301d-01
├─sdd2 /media/brad/12029A4D029A35A7 1.2T ntfs 12029A4D029A35A7 a4ed301d-02
├─sdd3 1K a4ed301d-03
├─sdd5 /media/brad/DATA DATA 99.4G ntfs 01CF6192E0BE96A0 a4ed301d-05
├─sdd6 EXTRA DISK 412.9G ntfs 01CF6192F99ED810 a4ed301d-06
├─sdd7 /media/brad/b6531485-cf61-4aa8-a84f-a974f7355816 77.2G ext4 b6531485-cf61-4aa8-a84f-a974f7355816 a4ed301d-07
└─sdd8 16G swap 436af5b9-2c2b-439c-8a94-aeb40e92faa6 a4ed301d-08
sde 1.8T
└─sde1 Seagate Expansion Drive 1.8T ntfs 80AA7070AA706496 7132b5cf-01
sdf 1.8T
└─sdf1 /media/brad/BACKUP BACKUP 1.8T ntfs 0FC707230FC70723 ebf3db09-c720-11eb-8376-2cdb0731dc5a
sr0 1024M
brad@brad-XPS-8940:~$ lsblk -o name,mountpoint,label,size,fstype,uuid,partuuid | egrep -v "^loop"
NAME MOUNTPOINT LABEL SIZE FSTYPE UUID PARTUUID
sda 931.5G
├─sda1 128M c2474ef3-06ab-4c08-a1fe-730170471c6f
└─sda2 DATA 931.4G ntfs E49830E99830BC3C 69f4abef-7d6d-4179-b2e5-67a0e8c87a9e
sdb 465.8G
└─sdb1 / 465.8G ext4 be63ac29-7656-4ace-95ef-72cf242637c3 2ff9e60f-7865-454f-97f7-c79187b7ad49
sdc 1.8T
├─sdc1 System Reserved 100M ntfs 342897B828977796 3119d5b4-01
├─sdc2 /media/brad/12029A4D029A35A71 1.2T ntfs 12029A4D029A35A7 3119d5b4-02
├─sdc3 1K 3119d5b4-03
├─sdc5 /media/brad/DATA1 DATA 99.4G ntfs 01CF6192E0BE96A0 3119d5b4-05
├─sdc6 EXTRA DISK 412.9G ntfs 01CF6192F99ED810 3119d5b4-06
├─sdc7 /media/brad/b6531485-cf61-4aa8-a84f-a974f73558161 77.2G ext4 b6531485-cf61-4aa8-a84f-a974f7355816 3119d5b4-07
└─sdc8 16G swap 436af5b9-2c2b-439c-8a94-aeb40e92faa6 3119d5b4-08
sdd 2.7T
├─sdd1 System Reserved 100M ntfs 342897B828977796 a4ed301d-01
├─sdd2 /media/brad/12029A4D029A35A7 1.2T ntfs 12029A4D029A35A7 a4ed301d-02
├─sdd3 1K a4ed301d-03
├─sdd5 /media/brad/DATA DATA 99.4G ntfs 01CF6192E0BE96A0 a4ed301d-05
├─sdd6 EXTRA DISK 412.9G ntfs 01CF6192F99ED810 a4ed301d-06
├─sdd7 /media/brad/b6531485-cf61-4aa8-a84f-a974f7355816 77.2G ext4 b6531485-cf61-4aa8-a84f-a974f7355816 a4ed301d-07
└─sdd8 16G swap 436af5b9-2c2b-439c-8a94-aeb40e92faa6 a4ed301d-08
sde 1.8T
└─sde1 Seagate Expansion Drive 1.8T ntfs 80AA7070AA706496 7132b5cf-01
sdf 1.8T
└─sdf1 /media/brad/BACKUP BACKUP 1.8T ntfs 0FC707230FC70723 ebf3db09-c720-11eb-8376-2cdb0731dc5a
sr0 1024M
brad@brad-XPS-8940:~$ ^C
brad@brad-XPS-8940:~$ cat /etc/fstab
/etc/fstab: static file system information.
Use 'blkid' to print the universally unique identifier for a
device; this may be used with UUID= as a more robust way to name devices
that works even if disks are added and removed. See fstab(5).
/ was on /dev/sdc1 during installation
UUID=be63ac29-7656-4ace-95ef-72cf242637c3 / ext4 errors=remount-ro 0 1
/boot/efi was on /dev/nvme0n1p1 during installation
UUID=3C4F-2D63 /boot/efi vfat umask=0077 0 1
/swapfile none swap sw
Yes, that's the only way that I can get back into Zorin, but it will only start in recovery mode.
ARNING!!! The filesystem is mounted. If you continue you WILL
cause SEVERE filesystem damage.
I recommend not doing whatever you are doing that gave you that warning. 
Okay, I canceled this, that was "file system check."--But where do I go from here to get everything back to normal (The way it was before I ran update and upgrade?)
Wow.... I wonder what went wrong, there...
I am sorry, I am still unclear about whether you see other Kernel Versions under the Recovery Advanced Options for Zorin menu.
If so, are you able to boot the computer by selecting an earlier version.
Side, note: That is a lot of Disk space.
It shows four choices under Zorin advanced options:
The first is just regular boot--with generic kernal 38.
The second option is recovery mode with generic kernal 38.
Third option is regular boot with generic kernal 37.
Fourth option is recovery mode with generic kernal 37. (This is the only one that works, and it goes through a couple of other questions before it finally loads Zorin.)
When you say "works"; do you mean the desktop is fully working? Or that it manages to boot, but is limited or otherwise broken?
As far as I can tell, everything that I have tried has worked.
I am in that mode right now, writing these answers to you.
Good. This means we have a sense of direction - that the kernel is the likeliest culprit.
Can you please remind me of your Graphics card: Intel? AMD? Nvidia?
You said that booting asks you a couple of other questions- what are those questions?
Nvidia card.
I cannot exactly recall the other "questions," mostly they were of the type where it says "Do you know if you continue, read-write will be enabled."
Can you please install the 5.11.0.27 kernel, then see if you can boot into it with the "Regular boot with generic kernel -27" option?
If it works... Then we can lock that kernel in and Remove the Rest.
sudo apt install linux-headers-5.11.0-27-generic linux-modules-5.11.0-27-generic linux-modules-extra-5.11.0-27-generic linux-image-5.11.0-27-generic