If you device won't boot and leaves you on a black screen, then you will need to power off the device and then hold down the LEFT button while you power it on. This could take up to 10 seconds.
Description
UP key = LCD driver 1
DOWN key = LCD driver 2
OK/SELECT key = Reset/Automatic detection
LEFT key = Updates 2021/12 QFP100 chip
Note: H2+ usually require you to hold the UP key on the first boot to configure them.