Thank you for your reply. I will look into it and let know how it went.1.73.8 changed partition table and require PC to flash firmware. Will erase everything include IMEI and zlink/360 activation. All can be recovered.
If you want to try, info here. It is quite a bit more complex than standard upgrades via System Info menu button. But not too difficult depending on computer skill level.
YT5760B_AC8259 - Brick Recovery
Firmware Format and Installation Diagrams Here is a general overview diagram providing an understanding of ota, firmware, and TWRP flashing. And flashing upgrade to 64bit on <= 4GB HUs. https://mega.nz/folder/hDEhFAqZ#A0JuPIKhW83X5NZgL2NSWg/folder/QTllgKwAsites.google.com