T-Class Fuses - testing, possibly blown, etc.

[WorldwideDave]

I have 4 different t-class fuses and 6 different fuses.
Finally got around to using the 5th t-class fuse, hooked everything up, and my system would not power up.
I measured for voltage everywhere, and thought maybe my inverter was bad, but then it turned out that actually it was the t-class fuse. Got voltage at the negative bus bar and the 'battery' side of the t-class fuse holder, but not at the other side of the t-class fuse holder. I then did a continuity 'beep' type test, and it didn't pass continuity. Swapped it out for the 6th t-class fuse, and then it started to work.
While on the bench, I was playing around with the burnt one. I do not recall seeing or hearing it ever go bad. It looks perfect on the outside. I think it is 250A rated. I never had a battery stop working charge/discharge. So I am deeply puzzled by this.
Maybe I bought a bad one/used one?
What other tests can I do with this thing?
No way visually to see that it's bad.

 

[ricardocello]

Maybe I bought a bad one/used one?
What other tests can I do with this thing?
No way visually to see that it's bad.

That is highly unusual. I assume there is no way you could have put more than 250A through it.
What brand is this?

 

[WorldwideDave]

That is highly unusual. I assume there is no way you could have put more than 250A through it.
What brand is this?

Littlefield (?) I believe. I’ll get some pix soon.

 

[SparkyJJO]

Littlefield (?) I believe. I’ll get some pix soon.

Littelfuse maybe?
Probably rare but still possible to somehow get a defective one.

 

[MattiFin]

Littelfuse maybe?
Probably rare but still possible to somehow get a defective one.

Amazon returns is how you get defective ones..