One of the LED manufactures we have used in the past released this guidance following COVID-19 lockdowns with regards to turning screens back on.
https://www.digiled.com/tom-mudd-advises-on-how-to-bring-your-digiled-screens-out-of-hibernation/
Generally after long periods of non-use / storage they recommends starting the wall at low brightness to 'dry' out the LEDs before going up to full brightness.
We have definitely seen failures on outdoor products when left off as the product cools down and water always seems to get where you don't want it.