Glad to see you are now booting PCLOS properly 
I will also have to validate how to address the issue related to chroot problem
Now that PCLOS is booting, what issue do you have with chroot?
What exactly are you trying to achieve with the command?
It is just for trying to boot similarly as LiveUSB, the others Distros mentioned in my first post.
For this aim, I will use another Pendrive, in order to keep my current PCLOS LXDE LiveUSB.
I have never used chroot for this purpose ........ in fact I could not even guess at how it might be used for the purpose ........
From any experiments I have done in the past it is a matter of getting the files onto the partition in the correct path, and then ensuring that the Grub entry is correct. But it is a few years since I did any extensive experiments in that area.
Just17: Thank you for your feedback!
BTW, paying attention to the first black screen with an error message at boot for PCLOS LXDE I notice that I still need to change (hd0,1) for (hd3,1) in some files. The screen passed so fast that I could not see more details. So far I made the change in menu.lst from the grub folder. Do you know how can I access a log file to see that error message in detail?
If you have the menu.lst file corrected properly then there is not much else for you to do.
Maybe you should check it again to be sure

Of course I have no idea if you have made some persistent changes which might affect something .......
Have a look for log files & dmesg under /var/log
What did you see that caused you to believe you need to edit some files?