User austin.bike asked this for the 530 over 5 years ago: https://forums.garmin.com/sports-fitness/cycling/f/edge-530/194899/how-can-i-turn-off-the-530-power-menu-just-want-1-click-power-down
Or at least have POWER OFF the default, and not SLEEP MODE. Using the up/down arrow keys each and every time to power off is ridiculous. Or make the PowerOff button "long hold" power it off.
Also, my new 540 would not power up this morning. No matter what I did.
So I had to do the secret button presses: press and hold Lap & Start/Stop at the same time, and while doing that, press the Power button. Wow, all these new features and graphics and settings and widgets, and the most basic thing - Power On/Off - is still faulty.
My old 520+ was easier to use (as was my 500, 300, and I can't remember the older ones).