Common causes for no display issues?

I have been looking for a color laser printer that can take heavy cardstock I may need to take on myself due to the world of copyright (think 110-120lb, but also light stock like 65-90lb) and I have a chance to get a Brother unit (albeit without toner) for a very good price, but the machine has been replaced by Brother and they did not want it back. The reason for this is a bad LCD, so they likely sent out a replacement machine without toner, hence why it doesn’t come with any.

I know I’m on my own with this and it may very well not come with the imaging drums, which are sold as a set only ($$$), so if I need to get those I’m done for unless the aftermarket has cloned these things. The drum isn’t an issue if it’s cheap, but if the ITB is worn there’s no way I’m buying that outside of Brother. It seems like the killer cost is going to be the ITB.

The reason I am looking at this Brother is the other unit I was looking is a CLJ M451dn (part of the Pro 400 series, which I know is a workhorse series like all of HP’s SMB lasers) but it has 140k pages, with some change and the price is kind of high especially with 140k pages PLUS a damaged ethernet jack, but it’s a trusted seller I know understands how to ship a printer - and it has a good amount of toner left on the C, M, Y and K toners so I do not need to worry about it for a while. However, my apprehension with the price is what I got my replacement M401n for $133 (8,871 pages) so the price they want for the M451 ($150) is kind of steep, but I’m happy with the M401n and the SJ Pro 2500 f1 from the seller. High page counts on a LJ Pro 400 series DO NOT SCARE ME, but the price needs to match with the 100k+ status on the machines in that group (which is frankly, a lot - especially from schools and offices). They’re like a well maintained Toyota or Honda - if it was taken care of, it’s just been “well driven” outside of potentially needing unknown preventative maintenance done, like the rollers and separation pads. I’ve had machines with 143k pages and in some cases, 250k on the clock - I’m no stranger to these “well used” LJ printers, and can spot a bum series which will never make it.

What causes these display issues on the Brother lasers? I may chance it, but it’s very conditional on the drum being reasonably priced just in case.