I'm not sure what you get with a recovery USB.
Let's try clearing the memory by shutting down and removing all power sources and hold the power button in for ~30 secs.
It may or not boot up after that but you can give it a try - I assume you don't have any external drives plugged in while you are trying to get it to boot up ?
If you have access to another machine, can you create install media after reading the instructions at
https://www.microsoft.com/en-gb/software-download/windows10This will comply with your version of 1803.
If/when you have done that, boot up with it and navigate to the Install screen and click on Repair your computer.
This will give you the same advanced boot options.
Select Command Prompt and enter these cmds -
bcdedit |find "osdevice"
For clarity that is a Pipe symbol before find and is the uppercase of \
Using that partition letter instead of the X I have exampled, enter -
sfc /scannow /offbootdir=X:\ /offwindir=X:\Windows
(note the space before each / )
Follow that with - again using your partition letter instead of my x
chkdsk x: /f
There are also a couple of bootrec cmds you can try, but I've never known them to work.
bootrec /fixmbr
bootrec /fixboot
You could get an error with that one.
Enter exit to close the cmd window, remove the install media and restart to see what you get.