@jay_s_uk you suggestion worked, i must have figured it out at the time but never committed the "!" to my config. Thanks so much!

@dc42 i was afraid of that but it seems like i was lucky.

First cut came out decent

@jay_s_uk i'll try that tonight, thanks alot. i'll report back.

@jay_s_uk it actually does, sorry forget to mention that.

Can't update my post anymore - sorry - so here is my config:
My Config:

; Configuration file for Duet WiFi (firmware version 2.03)
; executed by the firmware on start-up
;
; generated by RepRapFirmware Configuration Tool v2.0.3 on Sun Sep 08 2019 11:43:58 GMT+0200 (Central European Summer Time)
 
; General preferences
G90                            ; send absolute coordinates...
M83                            ; ...but relative extruder moves
M550 P"MPCNC"                  ; set printer name
 
; Network
M552 S1                        ; enable network
M586 P0 S1                     ; enable HTTP
M586 P1 S0                     ; disable FTP
M586 P2 S0                     ; disable Telnet
 
; Drives
M569 P0 S1                     ; physical drive 0 goes forwards
M569 P1 S1                     ; physical drive 1 goes forwards
M569 P2 S1                     ; physical drive 2 goes forwards
M584 X0 Y1 Z2                  ; set drive mapping
M350 X16 Y16 Z16 I1            ; configure microstepping with interpolation
M92 X100.00 Y100.00 Z400.00     ; set steps per mm
M566 X900.00 Y900.00 Z12.00    ; set maximum instantaneous speed changes (mm/min)
M203 X6000.00 Y6000.00 Z180.00 ; set maximum speeds (mm/min)
M201 X500.00 Y500.00 Z20.00    ; set accelerations (mm/s^2)
M906 X1700 Y1700 Z1700 I30     ; set motor currents (mA) and motor idle factor in per cent
M84 S30                        ; Set idle timeout
 
; Axis Limits
M208 X0 Y0 Z0 S1               ; set axis minima
M208 X579 Y578 Z150 S0         ; set axis maxima
 
; Endstops
M574 X1 S1 P"!xstop"
M574 Y1 S1 P"!ystop"
M574 Z0 S1 P"!zstop"
 
; Z-Probe
M558 P5 H5 F120 T3000 C"!^zprobe.in"               ; set Z probe type to switch and the dive height + speeds
G31 P500 X0 Y0 Z19.20575                      ; set Z probe trigger value, offset and trigger height
M557 X0:550 Y0:550 S50  
 
; Heaters
M140 H-1                       ; disable heated bed
M307 H3 A-1 C-1 D-1       ; Disable Heater output on H3
 
; Fans
M106 P0 S0 I0 F500 H-1         ; set fan 0 value, PWM signal inversion and frequency. Thermostatic control is turned off
;M106 P2 S1 I0 F500 H-1
M950 F2 C"!Fan2"
 
; Tools
M563 P1 S"Spindel" F0               ; define tool 0
G10 P1 X0 Y0 Z0                ; set tool 0 axis offsets
G10 P1 R0 S0                   ; set initial tool 0 active and standby temperatures to 0C
 
; Custom settings are not defined
M453 C"fan0" R6000 T1 ; CNC MODE
 
; Miscellaneous
T1                             ; select first tool
M106 P0 I-1

I've installed a cheap ebay laser controlled with pwm with the additional circuit from the pvm laser guide. When I installed it for the first time it worked as in i could cut cardboard with it.

Now a few months later i'm trying to get it running again with Lightburn hopefully, but my Laser turns on as soon as i put the machine in laser mode with :

M452 C"exp.heater3" R255 F5000

and only turns off if I reset the machine, it doesn't react to any of the following:

M5
M3 S0
G0
G1 S0

At this point i'm afraid i've fried some circuit which would explain why it's always on not so much why it turns off with the reset or stays off before i enable Laser Mode, right ?

My Machine:

• MPCNC burly
• Duet Wifi 2
• Version: 3.1.1

Thanks in advance!