I got some really weird stuff on the screen after I pulled the memory board out to replace the battery. It took a few restarts before I could even get it to start up so I could zero the memory.
I would definitely try the zero memory procedure. I would also recommend replacing the memory board battery if you don't know how old it is.
This video shows how to replace the battery.
https://youtu.be/OuYS4KLvQyk?si=DHiv9W20RDRymONw
This is the battery on eBay https://www.ebay.com/itm/184450539247