Struggling to install via USB

[gold_finger]

Once again, I wanted to check if its a good idea for a good config laptop (Intel I7, 6 GB DDR3L,nVIDIA GeForce 720 M).

Just because LL is light enough to run on lower end systems doesn't mean it was meant only for them.  Machines with better specs just run any OS better (faster) than a machine with lesser specs.  I run LL on new and old machines.  So, "Yes" running LL on your I7 machine is perfectly fine and, as N4RPS pointed out, it will be very snappy and quick.

karansh@karansh-Aspire-V5-573G:~$ ls /sys/firmware
acpi  efi  memmap

The output above does show that the live Linux Lite USB booted in UEFI/EFI mode.  (The "efi" would not have been listed in output of command if it had booted in Legacy mode.)

The other command ("parted -l") shows the partitions currently on your hard drive.  They look exactly the same as when you posted the output of that command earlier in this thread.  So, before we continue, I want to know:

1. Do you still have Xubuntu on the hard drive and are you still able to boot into it?
   
2. If "YES", did you have to re-install it after your latest attempt to install LL; or did it never disappear after your attempt to install LL and it just booted up as normal?  (In other words, after the failed install of LL, did Xubuntu still work?)
   
3. When you were trying to install LL, were you trying to install on the whole drive; or were you trying to install as a dual-boot with Xubuntu?
   
4. On your current live USB that you're using to boot and install LL, which program was used to create it?  (You mentioned using several -- which one made the USB you're using now?)
   

Based on your answers to the above questions, we'll proceed in one of two ways:

1. Try installing in UEFI mode.  (Since your live USB did boot in UEFI mode, I'm guessing it will install correctly -- but I don't know for sure.  One of questions I asked above may reveal a clue as to why your prior install attempt failed.)
   
   
2. Switch computer to CSM/Legacy boot mode and install LL that way.  That WILL definitely work, but involves changing boot mode in you UEFI settings menu and wiping the current partitions and reformatting the drive to MBR partitions instead of GPT partitions.  (Sounds difficult, but it's not.)
   
   

After you post back and are waiting for a reply, look-up how to get into your computer's UEFI Setting/Startup Menu.  (It might be referred to as "BIOS" settings.  That's technically incorrect, but many manufacturers seem to continue using that terminology even when the firmware is UEFI.)  Normally that is done by hitting a special key immediately after powering on the computer, but that key varies from one manufacturer to the next.  Sometimes it's the <DEL> key, or the <ESC>, of one of the function keys like <F2>.  You'll just have to look that up.

Normally there is also a separate key that you can hit that brings up a "Boot Menu".  Look up how to get into that as well -- we might need to know that later.  (Usually that's another key like <F12> or <F10> that's pressed on startup.)  That Boot Menu controls the booting for only that particular session booting the computer.  The UEFI/BIOS Settings Menu will have a boot menu in it also.  Changes there carry over on every bootup of the computer.  The separate Boot Menu allows you to temporarily change the settings for only the current bootup session without having to go into the full UEFI Settings Menu.