Case sensitivity matters on Linux-based recoveries.
The most common cause of the "Mnt Udisk update.zip" loop is a mismatched file. You cannot use a generic Android update. Mnt Udisk Update.zip
Always keep a copy of your working update.zip on a secondary PC drive. If an update fails, you can revert to the previous stable version using the exact same "Mnt Udisk" method. Case sensitivity matters on Linux-based recoveries