Live and learn indeed. This is important to show, IMHO, and I appreciate you doing so.

One thing to note about the Iridium: it is not an assisted open knife. However, as mentioned, the crossbar lock is very fidget friendly and you can very easily get a hang of pulling back on the lock and flicking the knife blade open to deploy the blade and having it lock in place at the end of your hand movement. Same to close it. You can also open and close it a variety of ways with the thumbstuds. A bit of practice and you'll get the hang of it.

I agree with dual_sport_dork@lemmy.world. The Iridium and the Ontario Rat would be my choices. I have the Ontario Rat 2 (a 3" version instead of the 3.5" that is the Rat 1) and it's rock solid. A great choice.
I don't have an Iridium but I do have other Kershaw knives with their crossbar lock (their marketing name being the Duralock) and they're also excellent.

You cannot go wrong with either of those.

And yes, the crossbar lock design has a lot of different marketing names: AXIS lock (Benchmade), Duralock (Kershaw), Pivot Lock (Gerber), Able Lock (Hogue), Clutch Lock (Kizer), Glyde Lock (QSP) etc. But many companies just use the term crossbar lock.

The usual answer is either a heat gun or a soldering iron tip to heat the threadlocker that is probably in there. But dual_sport_dork@lemmy.world is not a usual person 😂

In the $25-50 range, the world is your oyster, in the knife world that is for sure. Especially if seatbelt cutter and glass breaker are not requirements. And honestly, most of the glass breaker tips you see on knives don't actually do a good job doing that. (No experience with your particular knife, just an overall observation).

If you were to look at just KnifeCenter.com and just knives that are in stock today, you get 950+ choices for knives in your price range with blades between 3" and 4" in length.

https://www.knifecenter.com/kc_new/store_store.html?a=folder&instock=t&max_blade=4&max_price=50&min_blade=3&min_price=25&sortType=defaultDe

If you like the combo edge (partially serrated) there are lots of options as well. I don't think you can filter on that option though so you'll have to look through.

For trying different lock types (the term for the lock on your knife is: liner lock) you can also filter on the left side. I would highly recommend something with an AXIS/Crossbar lock because they are a lot of fun/very fidget friendly. :) But there are also lots of great knives with liner locks in that list too.

Feel free to ask any questions about brands, styles, etc. once you dig into the list. (Of course, you can buy most of these elsewhere if you have a favorite spot, but the KnifeCenter website is great for filtering/sorting etc. so at least you can get a handle on what's out there.)

The one nice thing about having 2 sets of torx drivers is that now you have 2 sets of torx drivers! 😁 One can wander off into some hidden area of a junk drawer or a forgotten tool box or something and you'll have a backup!

In all seriousness, if you do get it apart, snap a couple pictures and post a follow-up. There's good info in a tear-down, even if someone never buys the same knife, it's good to see how things work.

And if you get to the point where you would like any recommendations for a replacement, post that as well. :)

It appears, from the photos online, that what is holding the knife together is the pivot screw at the front (which you said you can take out) and 2 sets of screws at the back. One set right by the glass breaker and one set right behind the belt cutter. You may need to have 2 torx bit screw drivers, one on each side of the pair of screws turning in opposite directions. Likely there is a barrel with threads on both ends in between the two sets of screws and the barrel is free to spin internally. So you have to leverage one screw driver against the other to loosen them.

This knife is an assisted open knife, so perhaps the spring mechanism inside has figured out how to wiggle itself free (or whatever was holding the spring in place has broken). It might be challenging to put it all back together if you can sort out what might be happening.

If you don't have additional torx bits and a driver, the cost of those is going to be some good percentage of an exact replacement. Certainly there's value in learning how this thing is put together, but it might not be repairable in a cost-effective way.