This is the safest method. You do it from your web browser.
The machine will transfer the file, verify it, and then reboot automatically. Do not turn off the power during this time. Method 2: Using a USB Flash Drive xerox workcentre 7855 firmware upgrade
Create a folder named UPGRADE on the root of the drive. Place File: Put the firmware file inside that folder. This is the safest method
A failed firmware upgrade can "brick" your WorkCentre 7855, turning a $5,000 printer into a large paperweight. Follow this checklist strictly. turning a $5
Download the latest firmware (.bin or .dlm file) directly from the official Xerox Support & Drivers page.