Help! Utterly lost over heater decoupled error

I'm not the sharpest tool in the shed, so please bear with me.

I have a da Vinci 1.0. I've flashed it to Repetier 0.92. It took me a few tries before I finally succeeded, but the flashed firmware was working great!

I encountered the dread "Heater decoupled" error message and I've been on an odyssey to figure out how to fix it ever since.

I checked the fuse on the board. I came across conflicting advice between here and other sites on what I should be looking for, but I think I figured it out. I concluded that the fuse had blown, so I installed a 4 amp fuse on a fuse holder that I soldered into one of the  wires behind the plug for the extruder.

No change.

I read in a few places that the heater decoupled test might need to be tweaked so I tried adjusting it to different values according to what others had done.

No difference.

I checked the bed and it heats up just fine. I narrowed the issue down to the print head. I tried snipping the wires that power it and soldering them together to skip the notorious clip connectors.

No joy.

I did more research and tried checking the thermistor. I couldn't rule out that I might have damaged it when I was briskly cleaning the print head with my wire brush. I wasn't sure, but I suspected after looking it over that I might have pulled one or both of the thermistor wires. I ordered an E3D v6 print head and replaced the old print head and thermistor in one go. After a lot of careful checking, I tried tonight to use my printer.

No luck.

Still the dreaded heater decoupled message.

Maybe there are still more things I could be doing, but I think I have done everything I could find or think of at this point. I have a hunch that there must be a gremlin lurking in the Repetier software, but I had flashed my printer and replaced it at least twice now.

Does anyone have any suggestions?

Here is what the latest log on the screen read:

< 4:44:43 PM: FIRMWARE_NAME:Repetier_0.92 FIRMWARE_URL:https://github.com/luc-github/Repetier-Firmware-0.92 PROTOCOL_VERSION:1.0 MACHINE_TYPE:DaVinci EXTRUDER_COUNT:1 REPETIER_PROTOCOL:3
< 4:44:43 PM: Printed filament:347.23m Printing time:3 days 8 hours 22 min
> 4:44:43 PM: N26 M111 S6 *115
> 4:44:43 PM: N27 M111 S7 *115
< 4:44:43 PM: Echo:N27 M111  S7
< 4:44:53 PM: Echo:N28 M105
< 4:45:03 PM: Echo:N29 M105
< 4:45:13 PM: Echo:N30 M105
< 4:45:23 PM: Echo:N31 M105
< 4:45:33 PM: Echo:N32 M105
< 4:45:43 PM: Echo:N33 M105
> 4:45:49 PM: N34 M140 S90 *75
< 4:45:49 PM: Echo:N34 M140  S90
< 4:45:53 PM: Echo:N35 M105
< 4:46:03 PM: Echo:N36 M105
< 4:46:13 PM: Echo:N37 M105
< 4:46:23 PM: Echo:N38 M105
< 4:46:33 PM: Echo:N39 M105
< 4:46:43 PM: Echo:N40 M105
< 4:46:53 PM: Echo:N41 M105
< 4:47:03 PM: Echo:N42 M105
< 4:47:13 PM: Echo:N43 M105
< 4:47:23 PM: Echo:N44 M105
< 4:47:33 PM: Echo:N45 M105
< 4:47:43 PM: Echo:N46 M105
< 4:47:53 PM: Echo:N47 M105
< 4:48:03 PM: Echo:N48 M105
< 4:48:13 PM: Echo:N49 M105
< 4:48:24 PM: Echo:N50 M105
< 4:48:34 PM: Echo:N51 M105
< 4:48:44 PM: Echo:N52 M105
> 4:48:49 PM: N53 M140 S0 *115
< 4:48:49 PM: Echo:N53 M140  S0
< 4:48:54 PM: Echo:N54 M105
> 4:49:02 PM: N55 M104 S190 *125
< 4:49:02 PM: TargetExtr 0:190
< 4:49:02 PM: Echo:N55 M104  S190
< 4:49:04 PM: Echo:N56 M105
< 4:49:14 PM: Echo:N57 M105
< 4:49:24 PM: Echo:N58 M105
< 4:49:34 PM: Echo:N59 M105
< 4:49:36 PM: Error:One heater seems decoupled from thermistor - disabling all for safety!
< 4:49:36 PM: Error:Temp. raised to slow. Rise = 0.00 after 34093 ms
< 4:49:44 PM: Echo:N60 M105
< 4:49:54 PM: Echo:N61 M105
< 4:50:04 PM: Echo:N62 M105
< 4:50:14 PM: Echo:N63 M105
< 4:50:24 PM: Echo:N64 M105
< 4:50:34 PM: Echo:N65 M105
< 4:50:44 PM: Echo:N66 M105
< 4:50:54 PM: Echo:N67 M105
< 4:51:04 PM: Echo:N68 M105
< 4:51:14 PM: Echo:N69 M105
< 4:51:24 PM: Echo:N70 M105
< 4:51:36 PM: Echo:N71 M105
< 4:51:57 PM: Echo:N72 M105

I'm guessing that the error is pointing to the print head, but beyond that I have run out of ideas on why it is acting the way it is?