Unfortunately that's my experience too - those instructions dont work, and actually contradict the instructions for the unit i bought. Holding the 'set' button for 3s turns the unit off or on. I'm sure that with some thought a driver could be made to set the limits, given the Tuya app does it, but that's beyond me for now....
I've managed to work around the issue in my automations as the limits already set in the device (I bought it 2nd hand) are wider than those that I want. So I command the blind position to 0 for open, and 82 for closed using the driver by @amosyuen in this post: [RELEASE] Zemismart Zigbee Blind Driver
The blind then moves to the right open / closed positions in my automations which command a set position, however the open / close buttons on the device still drive the blind further than I want.
