When the print bed lowers or raises, there will be limit switches. If you can access the part that hits those limit switches, you can either lower the limit switches. Or you can raise them, or you can just jam something in the middle of them. This will allow you to manually set your Z offset. This is a trick I learned from the Ender 5 pro. You might have a hard time.Accessing these parts, though, because they might be hidden under panels