You can flash it with an SD pack, this is all at your own risk of course. [Only registered and activated users can see links. ] both before and after the flash. Check that there is no gupdate.gcd file in the device's .System folder, if present remove the GCD file before preceding. Ensure device is fully OFF, not just in standby. Extract the RAR file below directly to the root of a CLEAN microSD, insert card to device and power on [connect to a power source if battery isn't fully charged]. Wait for the flash to fully finish and the device to boot itself then remove the card.
In the root of the card will be a new file 'BUP_154.bin' which is your 'nonvol' backup. Keep it somewhere safe for the life of your device.
Version 8.50 is very new having only been released several days ago. Please report back the results if you decide to use the flash pack.
WARNING TO OTHER USERS: This pack is for C4 version HWID 2077 of 24x7/8 and 25x7/8 devices ONLY [aka 2xx7, 2xx8]. Do not modify it for use in other devices unless you know exactly what you're doing as you can very easily HARD-BRICK your device using a wrong BIN or HWID.