I'm taking a basic electronics course and we were working with bathroom fan timer circuits, I heard in the course you could adjust the length of the bathroom fan timer by changing the value of the potentiometer in the circuit. This was interesting to me because I wanted to change the length of the fan timer in our house.

I opened up the fan and found the potentiometer, tried to rotate it but it didn't want to move. Before I went further I poked around with my multimeter to see if capacitors were charged so I didn't hurt myself. With the multimeter I accidentally connected what I believe to be the mains wires, and blew a fuse in our house.

All is well and good, I have learned my lesson (I should have turned off the power at the breaker, I had believed that since the light was off no power would be in the circuit), but now the bathroom fan makes a disgusting whirring sound when it's on. Is there a simple solution to this or do I need to suck it up and tell our landlord I broke the fan and get someone more qualified than me to fix it?

Note: Yes I shouldn't have been messing around in the circuit, you are correct, I am not qualified, that was a mistake. My question here is about simple things I can do safely at the moment, or if it's sufficiently unclear what the right thing to do is so I should get someone more qualified.

Details that may be useful: I live in the UK