Sorry, I see now that you're using a Duet Maestro, so no replaceable fan fuse.
Since this is the hotend fan, you could still use the always on fan port. If fan port 1 and 2 are no longer working.
Actually. the fan 2 block has it's own voltage select jumper, how is it set? Perhaps it's not set properly and that's why your Fan2 port isn't working as expected.
https://duet3d.dozuki.com/Wiki/Duet_2_Maestro_Wiring_Diagram