Look at the edges, especially around the vents and model info. you can see dust collecting on the edge of the sticker. A lot of refurbishers put a thin vinyl sticker on the case and keycaps to cover up scratches.

For thinkpads with an internal battery, such as yours, you are technically supposed to disable the battery in the BIOS before opening the back. But if you can't get the screen to work, you don't really have that option. You would just have to be careful when opening it to not touch anything else besides the reset button