MK3S+ MMU3 Firmware Update Problem  

MK3S+ MMU3 Firmware Update Problem

I am running PrusaSlicer 2.7.4 on a Windows machine. I had no problem updating my firmware on my MMU2, but I can't update the firmware on my MMU3. I updated my MK3S+ to 3.13.3 and then went to try and update the firmware for the MMU3. The PursaSlicr automatically detects a port but then has an error flashing. I'm trying to flash, MMU3_FW3.0.2+878.hex. I have tried several times. Resetting the printer, power cycling, reconnecting micro USB, resetting the MMU, but I still get the same error of not being able to open the COM 10 port.

The error log shows:

Flashing Original Prusa Multi Material 2 & 3 Upgrade (bootloader), looking for VID/PID 0x2c99/3 or 0x2c99/4 ...Found VID/PID 0x2c99/4 at `COM12`, rebooting the device ...Found VID/PID 0x2c99/3 at `COM10`, flashing ...avrdude-slic3r -v -p atmega32u4 -c avr109 -P COM10 -b 57600 -D -U flash:w:0:C:\Users\bob.LAPTOP-BOB\Downloads\prusa3d_fw_MMU3_3_0_2_MK3S_3_13_3\MMU3_FW3.0.2+878.hex:i

avrdude-slic3r: Version 6.3-20160220-prusa3d, compiled on Apr 5 2024 at 11:28:31 Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/ Copyright (c) 2007-2014 Joerg Wunsch

Using Port : COM10 Using Programmer : avr109 Overriding Baud Rate : 57600avrdude-slic3r: ser_open(): can't open device "\\.\COM10": Access is denied.

avrdude-slic3r: Could not open port: COM10

avrdude-slic3r done. Thank you.