Heater test failure. Is Sandwich, Buddy and/or splitter board shorted?  

Heater test failure. Is Sandwich, Buddy and/or splitter board shorted?

Unfortunately, the screw holding the nozzle shaft in place became loose on the fourth toolhead. When loading filament the shaft was pushed downward and pulled the hotend heater cable off the dwarf board damaging the connector. I have replaced the dwarf board but continue to have an error when calibrating/testing the toolhead. 

I sent this explanation to support (fantastic service btw) and they have sent another dwarf board to try. 

For background this is what I have done up to now.

I followed all directions and replaced the board only to find that failure in the nozzle heater check.  It failed in the Preparing  and Heater Testing segments. Fan Test and Loadcell test successfully passed.

I followed the recommendations to troubleshoot the problem.  I also have an MK4S with the 115 mm connectors.

I also have spare parts for the thermistor and block heater.

I did the following:

1) I replaced both the thermistor and block heater. Result was the same.

2) I have extra heat blocks and nozzles and completely replaced this with the new units. I connected this to the new dwarf board with the same results; test failure.

3) I moved one of the functional heat blocks and wiring from position 5 on the XL into position 4 and connected the thermistor and the heat block heater cable. The result was a test failure.  When I moved this block and wiring back to position 5, position 5 past the test.

4) I tried another set of wires on the existing heat block that came with position 4 with the same test failure result.

5) I moved the functional heater block unit and nozzle from my MK4S with the 115 mm connectors that I had on the unit itself and attached it to the new dwarf board in position 4. The test failed again.  When I replaced this unit back into the MK4S, it passed all the tests.

I decided to test if it was a short in the motherboard.

I switched the toolheads as follows.

1) Disconnected the Cable Splitter from Toolhead 3 and 4

2) Connected toolhead 4 splitter cable to the third toolhead position and vice versa

3) Repeated the test. Now the Toolhead in the third slot (the moved toolhead 4) works so the dwarf board is functional).Toolhead 3  (now connected to the fourth cable) did not pass the Preparing and Heater testing segments of the Heater Check test.

It would seem that something shorted out somewhere and power is not being provided to power the heater.

My question is what I should replace:

1) The Sandwich Board

2) The XLBuddy Board

3) The XL Splitter Board ( I note that it has the fuses on it and wonder if this is the board that shorted.)

4) The Splitter Cable

I know nothing about electronics on this scale and would be most appreciative if someone could help me with next steps or if they know what board to replace.

Thanks.

Photo below is the original test. Has same result after the toolhead exchange of position between 3 and 4.

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