Hi Andrew,
That's a pity so my next suggestion is as follows.
Plug the microSD card into a PC and see if it is formatted as 'FAT32'. If is not 'FAT32' then download a format program (such as 'Seagate DiscWizard' or similar) and reformat to 'FAT32'. Please note that no other format will work, not exFAT, NTFS, or anything else.
Then re-run the Brennan process and see if it now works.
Regards,
Peter.