KA24DE - Cranks, doesn't start, used to have knock

[240SX nub]

Ooookay so I have a 95 240SX with the stock KA24DE. I can crank it, change the timing while doing so with the distributor, and it sounds like it really really wants to start, but it never does. Before it stopped working, it had a slight ticking sound that disappeared when the engine warmed up or was at something over 2000 RPM. Anyway, my brother hit a tree and drove it home - it had a knocking sound when he got it back, but I wasn't there to look at it. It started up once after he shut it off, only to have that horrible knocking sound tell me to shut it off immediately, and it hasn't started since then. When I try to turn the engine over I don't hear anything resembling a knock anymore either, but I remember I could when I tried to after it stopped firing up.

Friend and I took off the valve cover and looked at it while cranking it, but couldn't find anything wrong with that, so I guess I'll ask you guys for ideas.
Thought about bearings or rod knock, but I'm waiting on a trailer to take it to my friend's before we actually tear into the engine. Mainly posting here to get ideas on things to look for. I've never actually rebuilt an engine, but it looks like I need to, and I've got a couple good write ups bookmarked for reference on how to do it.

Also, the wreck didn't really (Or at least don't think would have) hurt anything on the engine, all that really happened is he smashed the headlight and turn signal and scuffed up the bumper some.

[compactfean]

If you have a knock loud enough to make you want to shut the motor off and it won't run now I would suspect pistons hitting valves. Time to do a compression test before you get to carried away

[240SX nub]

Would've done that already, but need something to dig the rings that seal the plug wires to the spark plugs out. Have my friend grabbing a long pick from his tools at work, and I'll check it tomorrow.

[240SX nub]

Okay, so compression is low as hell, and I heard the knock again today. Light knocking kinda sound. It also shudders like it wants to start even with zero fuel getting in the cylinders.

Anyway, guessing I've got some work ahead of me if I want this engine going again lol