Fan goes to 100% and stays there after turning bullet on

I recently did my first deeper cleaning of my R2 pro, which involved removing and cleaning the impeller fan and chaff filter following the Aillio videos. Afterwards, I turned it on to apply the FW updates to 79 and induction to 28 (which I have successfully done) but when I turn the bullet on, the fan slowly ramps up to full speed on its own.

I turned it off, then on again and same thing. It also restarted a couple times because of the update, but again the fan does the initial wind up, goes back down, then slowly increases in speed until it hits max speed then stays there. It stays that way even if I start preheat, start the roast, end the roast, etc. It only turns off if I turn the bullet off or if I take the chaff collector off.

Visually, it looks centered. It was pretty close to the 3mm off the body that was suggested in the video.

Could I have done something along the way to cause this? What is the fix?

I believe that the air pressure is not being measured correctly.
Make sure that the control board is correctly mounted on the front plate, if it is a little bit off, the pressure sensor tube will not be air tight → measures low pressure → ramps up fan to get correct pressure.
You can see the pressure in the display if you press the B Button. You will see a P in front of the pressure value. This value should in crease when the fan is spinning faster and faster, if not, the measurement is wrong.

It was the control board. I forgot to include in the original post that I also replaced the control board with a replacement one I got after I initially received my bullet. Changing the control board back to the original, it does not do the same thing and shows a P value of about 2.5 at idle. The replacement board stayed at 0 the whole time, even after cleaning some of the dust on the pressure sensor connection.

The question now, I updated the control board firmware on the replacement one. The original one is still at 46, but now the induction is at 28. Am I able to update the original control board to 79 when the induction is already at 28?

Yes you can still update it, but the way to do is different in FW 46 which I am sure you already know.