I picked up an inexpensive "open box - brand new" Ender 3 just after Christmas. Figured it was cheap enough to give up if I didn't like it, with enough open routes to tweak and improve if I stuck with it.
The display panel shows only a blue screen after assembly,though. Oddly enough, the only part not sealed perfectly (in its antistatic bag) was the panel. Packing slip noted it had been previously returned as it was "ordered by mistake." Got a feeling the prior owner swapped the panel out with a defective one, then returned it. Waiting on a replacement to ship out as a result.
That's next on my list, if the replacement panel doesn't fix the issue. Figured I'd go with the obvious solution first. Doesn't help that I took a long look at the list of the firmware available for the Ender 3, and figured I'd cross that bridge another day. Creality does not make it simple to identify what's what.
What kind of Ender 3 is it? I flashed mine when I swapped to the silent mainboard. If you can figure out what kind of board you have, and any accessories that plug into the board, you should be able to narrow it down quite a bit.