Android error: Unfortunately, the process com.android.systemui has stopped.

moondrake thought this was worth mentioning said
2

I have an elderly off brand tablet with a giant 11 inch screen that I wanted to put in the kitchen to use for watching YouTube videos while cooking and cleaning. I haven’t booted this thing up in a long time. I’m getting the above error. All the fixes online tell me to go to settings. I can’t open settings. No matter how many times I press okay, this error message will not clear and I can’t get to anything else. I can’t even get it tp power down. Does anybody have any suggestions for me? I’d like to salvage this tablet.