I want to replace the Operation Panel on the Dell B5645nf with another unit that is working.
I am using a Lexmark 812 manual and found a *disturbing/confusing note on the disassembly:

Control panel removal (Lexmark MX81x)
Warning—Potential Damage: When replacing the control panel, control panel board, or controller board, replace
only one component at a time. Replace the required component and perform a POR before replacing a second
component. If this procedure is not followed, the printer will be rendered inoperable. Never replace both the control
panel and the controller board without a POR after installing each one or the printer will be rendered inoperable.

*Never install or remove these components as a method of troubleshooting while operating in normal user mode.
See “Controller board/control panel replacement” on page 268.
Warning—Potential Damage: When a component has been installed in a machine and has been powered up in
normal user mode, it cannot be used in another machine
; it must be returned to the manufacturer. The machine
must be powered up in Diagnostic mode or the controller board, control panel boards, or control panel will become
locked.

Can I test Operation panel on another machine in safety mode?