Hi Dale, I’m Louie. Sorry you had to wait awhile but I’ll do my best to help.Initially, bear with us; re-confirm and post back with the complete model number of the Brother printer.
Appreciate the additional information.
Can you try set the scanner lock? Then release the scanner lock lever and then press Stop/Exit?
Based on the above, then it would require internal hardware check/repairs.
I checked the repair / Service Manual and it provides guides for troubleshooting, maintenance dis-assembly and assembly.
Are you then considering a DIY (do-it-yourself) repair approach?
More importantly, would you be comfortable working on the insides of the MFC-8840D ? ...LIVE?