After much irritation, I managed to get into the factory menu. Can we please fix the instructions in the OP?
2b) XL2420Z, XL2430T, XL2720Z and XL2730Z, XL2735 (reported also on XL2546, XL2540): buttons 3 and 4 with power off for 5+ seconds, and then pressing the power button while continuing to hold the buttons down, will unlock the factory menu.
3) button 5 enters factory menu.
The numbering of the buttons does not state if we're counting from the top or bottom, when in fact we are counting from the TOP (top button is 1, last button directly above power is button 5). The irritating thing is that the instructions for entering the service menu count in the
opposite direction, clearly mentioning "button 2 from the bottom".
Anyway, I know this is far less relevant all these years later, but it's no less irritating than it was 5 years ago the last time I tried to get into this menu using these instructions. If the monitor had real buttons it would make it easier to deduce which way is correct, but with these touch-sensitive buttons it's possible to spend several minutes attempting to mash buttons while never being sure if you're just not pushing them correctly (and therefore, one isn't registering as being held for 5+ seconds).
PLEASE edit the OP so that the numbering of the buttons matches BOTH sets of instructions. It's crazy to have them numbered differently within one post.