As above it appears that something critical to engine start and probably running operation is being routed through the widget. Once that DB15 (that's what it's called by the way) plug is unplugged from the widget you have effectively removed the widget from the vehicle. That would be your permanent fix, except for the fact that the engine computer is requiring a path through the widget to be intact for it to function. What you'll need to do is find someone familiar enough with the engine computer and it's wiring so as to place jumpers around the widget and restore the ORIGINAL wiring BEFORE this thing was installed as an aftermarket modification.
If you can find an actual manual for the widget where it shows how to install, and what wires to modify to insert the thing, you should be able to undo and restore the original wiring before the widget was inserted. This would be the best hope.
Remember this widget is not a stock factory item but installed later where they had to make changes in the original wiring to insert this thing in the circuits. Not impossible to remove and undo it, but it does require someone familiar with the engine, it's computers, and it's accessory sensors and such in order to CLEANLY remove this widget without leaving any further nasty problems if they do it wrong......be afraid, be very afraid, of that scenario.
They may remove it but leave you other problems. Good luck and find the best qualified to do this job, it's worth whatever it costs to get it right. And verify all systems work properly afterwords, Like Tach, Speedo, fuel gauges, Engine operates OK, etc. I see indications that this thing was reading all kinds of sensors probably used by other systems. They must be restored. It's only necessary to remove it electrically, not physically, from the bus. So you can leave it in place if you wanted to, as a decoration I guess, but the wires must be restored to the stock configuration.