Installed trisquel on ASUS E402M but lost usb boot thereafter

Here's a brief summary of what was done after shrinking sda5:
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/dev/sda1 272.6 MB (fat32)
/dev/sda2 16.8 MB (unknown)
/dev/sda3 199.2 GB (ntfs)
/dev/sda4 523.4 MB (ntfs)
/dev/sda5 100.1 GB (ntfs)
free space 200000 MB
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free space 510.5 kB
/dev/sda7 19.0 GB (ext4) / Format? 19000 MB
/dev/sda8 25.0 GB (ext4) /home Format? 25000 MB
free space 148.0 GB 148000 MB
/dev/sda6 8.0 GB (linux-swap) 7998 MB
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Proceed with install:
...The partition table format in use on your disks normally requires you to create a separate partition for boot loader code. This partition should be marked for use as a "Reserved BIOS boot area" and should be at least 1 MB in size. Note that this is not the same as a partition mounted on /boot. -- If you do not go back to the partitioning menu and correct this error, boot loader installation may fail later, although it may still be possible to install the boot loader to a partition. ...
I take the risk to fix things later.
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After install: user name field had following text in it:
SMBIOS-implementations-newer-than-version-2-7-are-not-fully-supported-by-this-version-of-dmidecode-E402MA
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All I need now is a way to boot into the system 'as-is'.

After consulting askubuntu forums how to make an EFI-bootable USB multiboot drive, I created one with a bootable ISO image of Trisquel 7.0. Regardless of that, I was always led to the MBR grub installed by Trisquel 6.0.1 where I was given a choice between Trisquel or a (never used) Windows10 recovery option on /dev/sda3. I was repeatedly forced to revisit BIOS settings that CHANGE WITHOUT NOTICE on the ASUS E402M that prevent me from repeating any kind of USB boot! Trisquel 7.0 live works. Off-line installation succeeded without Partman crashing if I first created the new partition for it using the live session before attempting install. Biggest annoyance is the touchpad on ASUS E402M - neither with Trisquel 6.0.1 or Trisquel 7.0 can I disable the touchpad. Disabling it in the BIOS works and then I can use a mouse, but resuming from suspend the touchpad comes back although it remains disabled in BIOS! There is also no access to screen brightness control whatsoever, it is at full brightness all the time, even at the grub stage. On an older ACER ASPIRE 5742G running full brightness, at least I could adjust it before handoff from grub. At least I can shut Trisquel 7.0 down without errors. I haven't tried updates yet. I will be back to report any changes :) P.S. would be good that the installer informs the user that GPT partitions exist, and prevent confusion whether to use Primary or Logical partitions where there are none. Further investigation reveals that the starting address of /dev/sda1 is with a 1 MB offset. Repeated installations don't seem to know about that. P.P.S.: Asus support for Linux users is currently just headings to non-entries there.

Please file one issue per issue and discuss things first on the forum.