Unresponsive Black Screen, Large Negative Counts

Hello, I’m looking for help troubleshooting a couple of issues with our Beckman Coulter LS6500 liquid scintillation counter. The display screen connected to our thin client terminal is completely black and does not respond. However, we can still run samples using the command card connected to our user profile and by pressing the Start button on the instrument's onboard keyboard, so it seems the counter itself is still partially functional. Has anyone run into this issue before? Could this be due to, a faulty cable or display, or something internal in the LS6500? We’re also seeing extremely negative CPM values (around -50,000 CPM) on samples we expect to have little or no radioactivity. Background subtraction is enabled, but our background levels are typically only 70–200 CPM. A little about our samples: -We’re using glass scintillation vials. -Our scintillation cocktail is Econo-Safe (Research Products International). -Sample prep has been consistent and there's no known contamination. A colleague who previously used this machine extensively mentioned that she thinks the problem might be the window that opens when the samples are elevated into the counter. She mentioned that if it sticks open, the counts will be off. I also found another thread online where someone suggested replacing the reflector housing as a potential fix, though I’m not sure if that’s relevant to our issue. Here is a link to some photos of our system: https://photos.app.goo.gl/hezEbTZkhe3CntHc7 Any ideas on how to resolve either issue — or even where to begin checking — would be greatly appreciated. Thanks in advance!

Equipment: Beckman Coulter - LS6500