I have Manjaro Nibia (KDE) installed in my PC. I have downloaded the retroarch package (from the official repository) and then pamac asked for a reboot.
Since then, the Login Screen does not launch and I am stuck in a black screen.
I can access the tty console and tried some attempts to make It work again.
1- The SDDM service is actually active but I get these errors that doesn’t make my login screen to be displayed https://i.postimg.cc/y81wP5dr/IMG-20210228-032709549.jpg
2,3- Some files https://i.postimg.cc/qqHFCDSw/IMG-20210228-033052828.jpg https://i.postimg.cc/xd7h91PW/IMG-20210228-033427847.jpg
4- The stuck screen (with SDDM) https://i.postimg.cc/d0DgMyG2/IMG-20210228-033748472-HDR.jpg
5- The stuck screen (with lightdm) https://i.postimg.cc/sXh8xC61/IMG-20210228-033945194.jpg
Yes, I suspect that is because the 5.4 version you just installed is an earlier version than the 5.9 you currently use. AFAIK GRUB will boot with the newest one. There are 2 approaches you can with after this:
The first is slightly more involved.
1.1. To use it, reboot your computer, but just after the BIOS output of “press button to enter bios” press Esc.
This will bring up the grub boot menu.
1.2. In that menu, use your arrow keys to navigate yo the Advaanced options.
1.3. In the Advanced options, select kernel version 5.4 to boot into.
1.4. If successful, uninstall 5.9 as previously said.
1.5. Continue as normal.
This method is slightly less involved, but requires another download, and if it doesn’t work, it is recommended to use the previous method to get a working system again.
2.1. Open a terminal and install version 5.10.
sudo mhwd-kernel -i linux510
2.2. When done, seeing as GRUB should reboot into the newest kernel version, reboot and it should boot into 5.10.
2.3. Continue to remove kernel version 5.9:
sudo mhwd-kernel -r linux59
2.4 If desired, continue with kernel installations and modifications as required.