Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
Try holding down the reverse button, and the button that makes the pressure foot go half-up or half-down... then holding those two, press the Power button and power On the machine.
Does the machine work basically?
What did you apply the update for, was there a problem? and where did you obtain the update?
I would suggest that, if the standard means of getting into service mode (or whatever the power-up mode with the two buttons held down is called) is not working, perhaps the machine is 'broken', period. The means of entering service mode on a machine is generally *not* altered by a firmware update, or a change in operating software.
But if you tell me the current status of the machine, and its reactions to what I am asking about, and if you also tell me the version of the update, then I may be able to instruct you further usefully. Thanks... and let me know, please.