As the printer's behaviour is determined in firmware,
I think it is a very good advice only to update the firmware if absolutely needed.
I did a forum search on "canon service mode" I checked a lot of the hits and I noticed that some of the printers that couldn't enter service mode by the user were of the PGI-x50/CLI-x51 generation. There were no reports of any of these printers successfully entering service mode.
A special case is the iP7250 printer that according to druckerchannel.de can enter service mode, but will not do so for forum members, see
this and
this. Are there different revisions of the iP7250 and its firmware?
There have been some guesses to why newer Canon printers can no longer enter service mode by the user. See
this thread by
@anwar qais . The MG5540 is of the PGI-x50/CLI-x51 generation. In the first post a service tool v 4410 is asked for and in
this post locking and unlocking of service mode is mentioned.
I have a Canon MG5550 that I tried to get to enter service mode. My first attempt was with the method that works for most PGI-x25/CLI-x26 printers with pressing the Stop/Resume button five times. The printer behaved normally with alternating lighting the power button and the warning light, and the LCD display turned white with no text. But the service tool did not work. I don't remember if the buttons were greyed out or there was an error message. If I try to enter service mode now, the printer either turns on normally or gets totally unresponsive with only the warning light on and doesn't respond to pressing the on/off button. Only disconnecting the the printer from the mains and waiting for maybe half a minute (for a capacitor in the power supply to discharge?) will revive the printer.
I think this confirms the locking of service mode by a wrong procedure and/or wrong version of the service tool as described by anwar qais.
I wonder if the newest versions of the Canon Pro printers can still enter service mode by the user, or they also have been blocked by needing a new procedure/service tool?
