Looking through the diagrams there again a quick an simple test you can to to verify the loom is with the plug to the lambda sensor disconnected and the relay for the rad fan check your continuity between your live feed in w/g to ground you shouldn't have any which would show a good circuit but if you do then you've a wiring short not internally in the sensor.
Aside from that looking at how the sensor works you have a live feed in(heater circuit) and a permanent ground(heater circuit) and your reference resistance reading to ecu (which is in terms of V) a short on the opposite side of the sensor on wire B(black or brown im not sure its hard to make out so ill call it B) shouldn't effect the fuse to blow as this is directly to body ground, unless if your 12v feed in and this wires are shorted together in the loom ( which could be the case) then that will blow the fuse.
The same goes for the wire W as this is the reference to the ECU you can see its the shielded wire this is the reference to the ECU or feedback from the sensor to the ECU so that the ECU can see what the AFR is this wire carries 0-1V to the ECU a short on this is unlikely due it its shielding but could still happen due to chaffing etc.
Ive attached another diagram again with the red line indicating the fault line and the fact that when you plug out the sensor the fault is gone that shows that it is on the red line to the sensor, the green is the ECU refence of 1v and yellow goes straight to body ground, upon visually inspecting the loom to the sensor and all looked ok fully trace the lines back and carry out a good visual inspection to confirm, if there is nothing blaringly obvious then you will have to start stripping the loom to find where, as you mentioned when you got the car you had to make repairs to the wiring for the temp sensor harness, it could be the case that the harness was damaged in various places and could be causing this, finding the reasoning as to why the fuse going is the easy part, finding the physical short is the fun part, sometimes you can be lucky and it is blaringly obvious where there is a kink/burn/squash/tear/chaffing point in the loom and other times not, ive come across a completely corded wire causing a 8v voltage drop in a 2016 VW golf and doing a visual inspection on the loom everything was perfect could not see how or where the fault could lie until i physically paired the loom back and seen the corrosion further looking on the loom there was a tiny tiny pin hole caused by someone previously "back probing" but probed the loom and not the actual connector and made a perfect storm for water ingress in the wire and a complete mind f**k to find.
Aside from that looking at how the sensor works you have a live feed in(heater circuit) and a permanent ground(heater circuit) and your reference resistance reading to ecu (which is in terms of V) a short on the opposite side of the sensor on wire B(black or brown im not sure its hard to make out so ill call it B) shouldn't effect the fuse to blow as this is directly to body ground, unless if your 12v feed in and this wires are shorted together in the loom ( which could be the case) then that will blow the fuse.
The same goes for the wire W as this is the reference to the ECU you can see its the shielded wire this is the reference to the ECU or feedback from the sensor to the ECU so that the ECU can see what the AFR is this wire carries 0-1V to the ECU a short on this is unlikely due it its shielding but could still happen due to chaffing etc.
Ive attached another diagram again with the red line indicating the fault line and the fact that when you plug out the sensor the fault is gone that shows that it is on the red line to the sensor, the green is the ECU refence of 1v and yellow goes straight to body ground, upon visually inspecting the loom to the sensor and all looked ok fully trace the lines back and carry out a good visual inspection to confirm, if there is nothing blaringly obvious then you will have to start stripping the loom to find where, as you mentioned when you got the car you had to make repairs to the wiring for the temp sensor harness, it could be the case that the harness was damaged in various places and could be causing this, finding the reasoning as to why the fuse going is the easy part, finding the physical short is the fun part, sometimes you can be lucky and it is blaringly obvious where there is a kink/burn/squash/tear/chaffing point in the loom and other times not, ive come across a completely corded wire causing a 8v voltage drop in a 2016 VW golf and doing a visual inspection on the loom everything was perfect could not see how or where the fault could lie until i physically paired the loom back and seen the corrosion further looking on the loom there was a tiny tiny pin hole caused by someone previously "back probing" but probed the loom and not the actual connector and made a perfect storm for water ingress in the wire and a complete mind f**k to find.