There are 3 ways to upgrade the firmware , easiest is Web Interface or PC Pro, some times you need to upgrade to perform password reset, to up grade with out logging into the system , this leaves USB method is the only way
Download the latest Firmware for CP10 or CP20 from the NEC Sharepoint Knowledge web site
SV9100 CP 10
NEC Knowledgebase > UNIVERGE SV9100 > Software > Main CPU > CP 10/CP20 > Rxx_SV9100 > USB Upgrade file
Extract it onto a USB Drive ... all in the root directory
While the SV9100 is still running insert the USB Drive , the first Red LED under the SERIAL interface should solid ON when successfully mounted
Now it is safe to Turn the system off , wait for all lights to turn off on the CPU , Hold down the load button, Turn on , count to 10 then release the load button.
The CPU will NOT reboot once complete .. ( unlike other methods )
3 LED's will flash in unison once complete ( approx 3-4 minutes )
Remove USB drive
Turn off system
Turn it back on
DO NOT HOLD LOAD BUTTON WITH NO FIRMWARE USB DRIVE , THIS WILL DEFAULT THE DATABASE