The fuse should be easy enough to test with a DMM - either that 5V exists on both sides (preferred method), else low-Ohms resistance in BOTH directions, but that has a risk of blowing sensitive circuitry.
When told that the fuse "is 90% the fault", did that exclude other components being blown (eg, MOSFETs etc)?
If blown, see if the fuse can be extended - ie, solder wires to existing fuse to an external fuse. Otherwise piggy-back the new fuse.
Of course if something else caused it, it may just blow again (hence test current first with a DMM).
Check with Littelfuse, Digikey, Farnell etc.