U need to download this file if u are updating:
https://download.os-source.co/brax3/iodeos/v7/7.5/iode-7.5-20260519-brax3-ota.zip
Check the sha256sum with this:
https://download.os-source.co/brax3/iodeos/v7/7.5/iode-7.5-20260519-brax3-ota.zip.sha256
If all good then in the updater tap on 3 dots in upper right and choose local update. Then choose that first zip file.
EDIT:
I checked the integrity of that zip file using the DeadHash app and the sha256 file that BraX provides: