The right approach would have been to read Daz's FAQ what to do to make the loader running. For instance this: Go to the advanced options and select to disable type 4 memory, install the loader again and see if that cures it. If you're not cured try to disable type 3 memory instead. If it still fails try selecting the legacy setting. Since the loader only works on MBR and it said 'successfully installed' it makes no sense to look for GPT solutions. Either way your windows has been altered now and is inconsistent to the original. Also I wonder why MBR got damaged at all and if you really have installed an original OS coming from an original ISO. 'You are using an illegal copy' never appears when an original ISO has been installed and left untouched. The only reasonable way to activate w7 ultimate is Daz loader or a BIOS mod.
In my experience, I was unable to properly "genuine"-ize my Windows 7 Ultimate on GPT/UEFI. I had limited success with the Windows 7 Downgrader from Ultimate -> Professional to activate, it broke some things and I just reinstalled from scratch. However, Professional installs and activates fine on GPT/UEFI. On the other hand, it seems like there's no issues with getting Ultimate to activate on MBR/UEFI? Correct me if that is incorrect.
Pro and Enterprise can be easily activated by KMS on GPT, DAZ loader can activate all, except Enterprise, on GPT, but only when there is a valid slic in the bios.
maybe I can try to install & activate Win7 ultimate edition on my dad's Toshiba Satellite C55Dt 2013 laptop on a spare blank hard drive. that laptop uses UEFI/GPT and there's already a valid slic 2.1 table in the bios (toshiba already added the slic as well as an msdm table for win8.1)