Re: Lenovo Ideacentre B540 All-in-one - Black Screen

if you are able to do a factory reset, or at least start it with the recovery button. Do these steps:

Note: Please back up all your data as running this reset will delete any data on your machine

1. Turn the machine off and press the recovery button which is located usually next to the power button. If you have a desktop machine you will need to power the machine back on and keep tapping the F2 key.
2. Use the arrow keys and press enter on system recovery. ( Desktop users can skip this)...