Acer G215H monitor power supply slow to start

I have two identical Acer G215H monitors. Closest service manual here is for Acer G225HQ Qisda version One still works fine. The other has started doing: Press power button power LED and backlight turn on immediately turn off wait 5 seconds power LED starts blinking wait 5 seconds backlight blinks 5 times, 1 per second wait 5 seconds more backlight turns on, power LED turns on steady, monitor works fine I've already checked the capacitors and they're either bigger than my meter can measure, or the rated capacitance. help?