Hi,
I have installed EndeavourOS and was using Windows. During the installation I deleted Windows and installed EndeavourOS but then it asked me to restart my PC and so I did. After the restart though I can’t boot my PC at all. When I turn it on it is continuously stuck on a black loading screen.
I can’t open BIOS or boot from a flash drive. Anyone can help?
Welcome to the forum! 
This should help in how to get into your installed system:
https://discovery.endeavouros.com/system-rescue/arch-chroot/2022/12/
Then you can show some logs about the installed system:
https://discovery.endeavouros.com/forum-log-tool-options/how-to-include-systemlogs-in-your-post/2021/03/
which help us help you.
EDIT: you should be able to use your installer USB drive since you were able to install. How are you trying to boot the USB drive?
When I plug the USB and start my laptop nothing happens, it is just stuck on a black screen. I also can’t access BIOS so I am unable to check boot order.
When you boot, you should immediately press and keep pressing a special key.
The key depends on your machine. It can be one of the function keys, typically F1, F2, F8, F9 or F10. Sometimes ESC is the key.
Did you try this?
Yes, I do know how to open BIOS. My BIOS key is F2 but it stopped working after I did the install.
Disconnect your disk.
Restart your machine.
See if you can get into BIOS and/or boot up the live usb.
If you can boot the live usb, use the log tool and post the URL you will get.
Check as many boxes as possible to provide the forum with enough info about your system.
Perhaps some of our members could look into it and come up with some idea about what to do to make your system boot with EnOS installed.
Good luck!
The method by @pebcak is worth trying, it could provide useful information.
If that doesn’t help, I’d try also unplugging power (and possible battery) for a few minutes. And even the motherboard clock battery temporarily to make as complete machine reset that is possible.
Anyway, I suspect deleting Windows might have caused this problem to begin with. But let’s not jump into more conclusions before trying all possible tricks we can think of.
Edit: could you tell us technical information about the machine? The more detailed, the better.
So I have disconnected my SSD (where EnOs was installed) and booted up. Then it allowed me to boot from an USB finally. So evidently my SSD is most likely corrupted and I believe that the reason for it is that I have an NVDIA graphics card but during the installation I didn’t choose the NVDIA setup option. I didn’t even know it existed.
Regardless, now I have my SSD removed and when I connect it my laptop automatically wants to boot off of it so I need to install EnOS to my HDD. After I will have EnOS installed on my HDD I will try to connect my SSD again and then delete everything in it and then install EnOS on it again. But when I try to install EnOS to my HDD I get this error during the end: Installation failed: “Boost.Python error in job "bootloader".”
Here is the full log: https://termbin.com/k1vy
Without your SSD connected, go into your BIOS/firmware settings and give boot priority to USB Flashdrive. It should be under some tab called “Boot” or some such.
This should boot your machine off of the installer usb even when your SSD is connected.
Now, boot up your installer with the Nvidia option. Once in the live session, launch Gparted and create a new partition table. I suppose you have an UEFI system and you have booted your USB in UEFI mode. Create a GPT (Guid Partition Table).
Creating a new partition table will wipe out your whole disk. If you have other partitions or OS installed on the disk, don’t do this!
Next launch the installer and go with automatic install and accept the defaults.
If the installation fails, launch the log tool included in the live USB. Check all the boxes and let it generate a URL that you can post here on the forum.
It doesn’t work even though I do set the USB to be the number one boot prior option I think it automatically gives boot priority to my SSD.
The bootloader error seems to be about not able to create folders.
How did you choose the efi mountpoint?
What exactly does “choosing the efi mountpoint” mean? I am fairly new so please bear with me.
In the installer you can choose where you assign various partitions, and one of them is the ESP partition for UEFI installs.
EndeavourOS assigns the ESP partition to a directory (mount point) named /efi on the main install disk.
According to the log, your /efi resides on the installer USB, which is not what you want.
Also, you have a large Windows partition on the disk. You said in the first post that you deleted it, but did you reinstall it?
It is crucial to set the partitions correctly and assign the mount points to the required partitions.
So, you might want to reinstall again.
In the log your target disk is /dev/sda, and the USB installer stick is /dev/sdb.
On /dev/sda you have two partitions:
You probably want to remove Windows partition and create two partitions (at least these):
While installing, make sure you have something like this on /dev/sda.
You can use command
lsblk -fm
to verify this. The installer should create them automatically unless you select otherwise.
So what I did is I connected my SSD to another laptop and cleared it from there. So when I connected the disk back to my original laptop everything was fixed. Then I installed Endeavour OS again this time with the Nvdia option. But again the same thing happened. My computer locked with no access to bios or any other USB boot at all. So apparently the problem is about EnOS itself.
You never gave us any “hardinfo” about your system to go by 
The third time is the charm?
You are trying to use an external installation on different machines? This can hardly succeed…
No, I just connected it to another laptop and cleared it and then installed EnOS in my original laptop so no external install.
Then again:
https://discovery.endeavouros.com/forum-log-tool-options/how-to-include-systemlogs-in-your-post/2021/03/
hmm it could be an issue inside Bios Settings too… in case …
it must be set to:
And creatung teh installation Medium have to copy the ISO as it is and not changing the boot in any way.
like you can check here:
https://discovery.endeavouros.com/installation/create-install-media-usb-key/2021/03/
And always use the latest ISO older ISO can have issues when using online install method.
Only to may hint on any issue produced while install process.
I suggest
cat $HOME/endeavour-install.log | eos-sendlog
and show the returned URL here.