HP L2683A (HP ScanJet Enterprise Flow N9120 Document Flatbed Scanner) Won't Scan

[klepper]

I emailed this to tech support, but they wouldn't reply.

I have been a tech for 20 years, so I'm not unskilled at troubleshooting. 

So, I hook up to W10 machine just fine, all software installs, I see the device in the Device manager, when I press the hardware buttons it opens up the app in windows just fine.

However, the Yellow "!" An exclamation point is flashing after I turn it on.

And when I try to scan with HP Smart Document Scan Software 3.7.1 it says:
The scanner hatch is open. Please close it. EX = 1103

With HP Document Copy it says:
Document Feeder hatch is open. Close the hatch and click OK.

Windows Fax & Scan it says
Could not Complete Scan

Sometimes I've seen: "A scanner error has occurred. Be sure the scanner is properly connected and turned on. EX = 2216"

HP Print and Scan Doctor does not find the scanner.

All doors and hatches are FIRMLY shut, I've even tried to hold them each down more shut, if possible. I've checked all the latches, they all seem in fine condition. And yes, the scanner lock is off, I've checked it many time, with flashlight, the slider works just fine and it's for sure off/unlocked.

I have the Service Manual. I am wondering if this error is relating to:

ADF Jam Door 1?
ADF Jam Door 2?
OR
Jam door 1 sensor.
Jam door 2 sensor.
Jam door 3 sensor.

I don't mean to ask you to fix it, but can you help me at least troubleshoot it? I know this is beyond the end of service life.

1. Can anyone give me a link to the "N9120 Service Tool"?
2. Can anyone tell me which sensor it is?

If I just take it a part unplug this sensor, will that work?