Problem Ubuntu 20.04 LTS iso file

https://ubuntu.com/download/desktop
Try using Etcher to make your live USB.
https://etcher.download/download-etcher/

Use Etcher to make two live USBs tried both but still the same.
After 20 seconds after booting on maroon screen the screen goes black with only ubuntu name
at the bottom and stops.

Your downloaded .iso file must be corrupted in some way.
I downloading the same .iso file from the above link, to check it.
Everything works absolutely fine.
Check the computer you are installing it on have the min. requirements.
2 GHz dual core processor
4 GiB RAM (system memory)
25 GB of hard drive space

The maroon screen then a black screen let program finish loading then you will see the orange screen with the focal cat on it.
Then the installer will start. Try Ubuntu or Install Ubuntu screen.
Patience, it takes a while to load the program.
After you install Ubuntu and after the first restart. Same applies, Patience.
You will see a screen with Ubuntu and a spinner. Then it goes to a black screen, Patience.
First the login screen. Then Ubuntu loads into the operating system.

Waited 20 minutes and nothing happen.

I am not able to understand what there is happening when you try installing Ubuntu.

If you boot your system from the installer USB device, what exactly happens?
Do you get the choice between "Try Ubuntu" and "Install Ubuntu"?

Installing from USB it stops at maroon screen with Focal Fossa date and time on Top Bar
with four icons on the end and cursor, the time is not working can move the cursor around
but clicking on any of the icons there is no action dont get to see "Try Ubuntu" and "Install Ubuntu"
screen.
Tried to install on old laptop HP 620 and surprise it boot correctly right to "Try Ubuntu" and "Install Ubuntu" option.
This PC os that I am writing this is Ubuntu 20.04 LTS I installed this year I been having a few
problems with it, one of the problems is taking nearly four minutes to boot.
The first iso USB got some problem and I had to make a new one I wanted to install on bigger
HDD when this problem developed.
I see the problem is hardware.

You might try using a lighter weight OS like Lubuntu 20.04 on older computers.
Minimum System Requirements
CPU:1GZ
RAM: 500MB
HDD: 20GB
OS: Lubuntu
https://lubuntu.me/

This PC specs are:
CPU: Intel Celeron CPU G1840@2.80GHz x 2
RAM : 7.5 GiB
HDD: 500.1 GB
It had worked before with Ubuntu 16.04 and now has 20.04 LTS version.
The problem came about when I decide to install on new bigger HDD.

Found the answer for the problem nomodeset option when booting from Ubuntu live USB.
It worked for me.
https://askubuntu.com/tags/nomodeset/info