PyInstaller ImportError DLL not found when testing EXE on other computer

The error you post just says "I was looking for one specific DLL and did not find it".

Rather than installing other packages and extensions that might, or might not, be or somehow contain the right DLL, you now need to determine exactly what it is that isn't to be found.

I can suggest three complementary methods, none absolutely certain to pinpoint the exact problem (of course the voodoo method of "install some package at random and see whether it fixes it" might also work, and often does -- but that's magic, not computer science):

• the quickest: check the pyimod03_importers.py file at line 714, see what it was doing when the exception was thrown. Due to Windows' library loading strategies, you might be handed a red herring, with a file reported not to be there when it actually is, because it relies on a second missing file whose name you won't be told.
• the easiest: use a tool like SysInternals' DEPENDS.EXE to inspect the OMR.EXE file. This is almost guaranteed not to work in this case, because the needed imports might be specified in Python format, not in any form that DEPENDS.EXE will recognize.
• the most comprehensive, but least easy: use a tool like SysInternals' PROCMON, set up the filters to exclude the background noise of Windows' idle state - there will be an awful lot of that - and then fake running OMR.EXE; exclude the additional noise generated by that. You'll need about fortyish filters to be set up. Finally run OMR.EXE. Near the end, you will see a series of attempt to load SOMETHING.DLL, all failed; the first is where the DLL is supposed to be (by either Python or OMR), the others are all suitable alternatives.

Then:

• if the DLL is one of yours, find out how to pack them with the EXE bundle.
• if it is not, you need to reliably assess where it can be found.
  • It might well be that the suggestion you were given - install MSVC redistributable that-version-or-other - was absolutely correct. Libraries with names like MSVCnn... belong to that package. MSO... files usually belong to Microsoft Office redistributables. MSJET... files are found in several Microsoft package, for example the .NET redistributable.
  • otherwise, Google and possibly MSDN Search Engine are your friends.

From past experience, I suggest setting up a virtual machine for testing, then seeing what packages are needed. This is because the first DLL crash will hide any subsequent ones, and you might need to repeat the above steps several times. The fact that the first library you need is supplied by the NETFX64 package and the second by the Microsoft Office runtime might be true, but when you find out that the second library is needed, you might also find out that the MSO runtime would have supplied the first also; so at that point, and not before, you discover that the NETFX64 package wasn't really needed, and can simplify your installation requirements to the MSO runtime alone.

Boiling down the requirements to a short list might be a lengthy task and you will want to restart the machine from scratch more than once. With a VM, that is easy to do.

(I've kept referring to the MSO runtime because I figure that your program will process a checkbox answers module, and will likey need or believe it needs some scanner recognition features, which the MSO runtime supplies. If that is so, they'll probably come last).